The artwork on the cover is a conceptual image of a layered two-dimensional solid 

state structure, to be created by computationally directed synthesis, where the 

quantum properties of individually-placed atomic states and their spins may be 

manipulated and entangled with photons, electrons, phonons, electric or magnetic 

fields.

Image courtesy of David Awschalom and Peter Allen, University of Chicago and 

Argonne National Laboratory
Report of the Basic Energy Sciences Roundtable on 

Opportunities for Basic Research for 

Next-Generation Quantum Systems

October 30–31, 2017

Gaithersburg, Maryland

Chair: David Awschalom, University of Chicago/Argonne National Laboratory

Co-Chair: Hans Christen, Oak Ridge National Laboratory

Participants:

Aashish Clerk, University of Chicago

Peter Denes, Lawrence Berkeley National Laboratory

Michael Flatté, University of Iowa

Danna Freedman, Northwestern University

Giulia Galli, University of Chicago

Stephen Jesse, Oak Ridge National Laboratory

Mark Kasevich, Stanford University

Chris Monroe, University of Maryland/IonQ

William Oliver, Massachusetts Institute of Technology

Chris Palmstrøm, University of California–Santa Barbara

Nitin Samarth, Pennsylvania State University

Darrell Schlom, Cornell University

Irfan Siddiqi, University of California–Berkeley/Lawrence Berkeley National Laboratory

Toni Taylor, Los Alamos National Laboratory

Birgitta Whaley, University of California–Berkeley

Amir Yacoby, Harvard University

Jun Ye, JILA, University of Colorado

Basic Energy Sciences Team: 

Linda Horton Jim Horwitz Mick Pechan

Bruce Garrett Refik Kortan George Maracas

Jim Murphy Matthias Graf Tom Russell

Jim Davenport Jeff Krause Tom Settersten

Katie Runkles, BES Admistrative Lead

Oak Ridge National Laboratory Publications Team: 

Brenda Wyatt, Deborah Counce, and Kathy Jones

https://science.energy.gov/bes/community-resources/reports/

iii

Contents

Abbreviations, Acronyms, and Initialisms ...............................................................................................v

Executive Summary..................................................................................................................................vii

1. Introduction.........................................................................................................................................1

Opportunities to advance the scientific understanding that will enable QIS.........................................2

Opportunities to advance instrumentation for the study of QIS, and instrumentation based on 

QIS approaches...........................................................................................................................2

2. Priority Research Opportunities .......................................................................................................5

PRO 1: Advance Artificial Quantum-Coherent Systems with Unprecedented Functionality 

for QIS ........................................................................................................................................5

PRO 2: Enhance Creation and Control of Coherence in Quantum Systems.......................................13

PRO 3: Discover Novel Approaches for Quantum-to-Quantum Transduction...................................19

PRO 4: Implement New Quantum Methods for Advanced Sensing and Process Control..................25

3. References..........................................................................................................................................33

Appendix A: Workshop Participants......................................................................................................41

Appendix B: Workshop Agenda..............................................................................................................45

v

Abbreviations, Acronyms, and Initialisms

1D one-dimensional

2D two-dimensional

3D three-dimensional

BES Office of Basic Energy Sciences

CVD chemical vapor deposition

DOE Department of Energy

EELS electron energy loss spectroscopy

IFM interaction-free measurement

MBE molecular beam epitaxy

MZM Majorana zero-mode

NV nitrogen vacancy

OPTS odd-parity topological superconductor

PRO Priority Research Opportunity

QIP quantum information processing

QIS quantum information science

QS quantum systems

SQL standard quantum limit

STEM scanning transmission electron microscopy

STIRAP simulated Raman adiabatic passage

ZBP zero bias peaks

vii

Executive Summary

For decades, scientists have predicted that devices based on “quantum phenomena” will be able to store 

and manipulate information to provide radical new approaches for computing, communication, and 

sensing. However, only recently have quantum phenomena been incorporated into technologies for nextgeneration computers, sensors, and detectors that demonstrate performance characteristics rivaling those 

of their conventional counterparts. These devices clearly demonstrate the enormous potential for future 

quantum-based technologies. The novel quantum device capabilities currently envisioned include 

enhanced resolution in imaging, sensors, and detectors; advanced cryptography for more secure 

communication; and significantly larger computational capabilities at speeds far greater than those 

possible in classical computing. However, realizing these advances requires a detailed understanding of 

how quantum systems (including quantum materials or assemblies of trapped ions and electrons) behave, 

accurate knowledge of how to integrate the components into complex systems, and precise control of the 

structures. In this context, creating and controlling quantum states within molecules and materials offer 

exciting scientific opportunities for fundamental research, as well as for enabling next-generation 

quantum-based technologies. Numerous questions remain, ranging from how quantum interactions may 

enable innovation through the creation of novel quantum systems, to how these new quantum 

technologies can advance our understanding of matter and chemistry at the most fundamental levels.

To address these questions and identify priority research opportunities (PROs), the US Department of 

Energy (DOE) Office of Basic Energy Sciences (BES) convened a roundtable of experts in quantum 

materials and quantum systems encompassing the fields of physics, chemistry, materials synthesis 

science, device engineering, detector technology, and atomic-scale characterization techniques. This 

group of experimentalists and theorists met on October 30–31, 2017, to explore scientific research 

opportunities in this rapidly moving field, in which BES support can play a key role in advancing and 

utilizing quantum information science (QIS). The goals of this roundtable were to define the unique roles 

for BES in this active research field and to provide input on future research directions, forming the basis 

for a coordinated, long-term research effort that will enable major advances in quantum-based science and 

technology. BES is uniquely positioned to advance this field because of its long history of fundamental 

research support for both materials and chemical sciences, along with its construction and operation of 

world-class scientific user facilities. Fundamental research in this area is strongly coupled to DOE efforts 

in scientific computing, high-energy physics, and accelerator/detector research and related to activities in 

“Beyond Moore’s Law” computing, next-generation semiconductor materials, and exascale computing.

The conclusions of the roundtable, highlighting the basic research challenges for both science and 

instrumentation, were summarized with four PROs:

Advance artificial quantum-coherent systems with unprecedented functionality for QIS

The synthesis of materials with pre-designed characteristics that are optimally suited for quantum 

information applications is a key requirement for the future. This PRO highlights the need for research 

that will lead to the development of new capabilities for real-time feedback and control of synthesis that 

are coupled with predictions and measurements of targeted quantum characteristics. This feedback would 

consist of both characterization and computation-based machine learning to optimize a material for the 

prescribed function. The PRO discusses opportunities in robotic synthesis of layered materials, quantum 

properties of hybrid (organic and inorganic) systems, the creation of topological states of matter (such as 

odd-parity topological superconductivity), and precise control to position atomic defects.

Enhance creation and control of coherence in quantum systems

Quantum-coherent systems have been discovered that exhibit remarkable properties and ever increasing 

coherence times. However, understanding of how these systems interact (for example, the complexity of 
viii

entanglement) is currently limited to a small number of systems. Advances in this field require an 

understanding of the scaling of coherence lengths and times with system size and complexity, and the 

identification of new signatures of quantum states in artificial quantum-coherent systems, as described in 

the previous PRO. Additional research is needed to understand the mechanisms that lead to decoherence 

in open quantum systems, which could facilitate control of coherence beyond adiabatic limits and result in 

discovery and exploitation of novel entangled excitations.

Discover novel approaches for quantum-to-quantum transduction

The coherent transduction of information from one modality to another, at the single-particle or quantum 

level, is at the core of quantum measurement and information processing. This PRO identifies primary 

research needs in generating and stabilizing nonclassical states of light and matter, transferring complete 

wavefunctions between disparate physical systems, quantum state replication and entanglement swapping, 

and transferring single quanta with high fidelity. Specific challenges are identified for infrared and 

microwave single photon detection, light-to-electron transduction, maximization of quantum coherence, 

and development of theoretical approaches for understanding quantum state transfer in realistic settings.

Implement new quantum methods for advanced sensing and process control

In contrast to the first three PROs that address materials and chemical sciences issues that need to be 

addressed to develop quantum systems, the fourth PRO focuses on the use of quantum-based systems to 

enable new research capabilities. In particular, this opportunity includes the deployment of extreme 

sensing, detection, and control capabilities for precise measurements of time, space, and fields, as well as 

the development and application of these capabilities to probe material properties and chemical processes. 

Advances are needed in designing sensors and detectors based on correlated materials; techniques to use 

squeezed states for metrology; quantum systems for high-resolution and high-sensitivity imaging;

quantum sensors for real-time monitoring and control of chemical reactions; and establishment of

connections between entanglement and thermodynamics.

The roundtable participants concluded that successfully addressing these challenges will enable the 

creation of next-generation coherent quantum systems with unprecedented performance for applications 

in QIS. The participants also noted the importance of creating metrics and design rules for quantumcoherent materials. If successful, the proposed research will result in the ability to create novel material 

platforms through the rapid survey of robotically synthesized structures and the subsequent convergence 

toward materials with desired quantum properties. Furthermore, these studies will provide new insight 

into the physical sciences based on ultrasensitive quantum sensors. For both QIS and many quantumlimited sensors, it will be important to reduce the effects of decoherence to create robust quantum states.

Once a next generation of quantum-coherent materials is established, large-scale quantum manipulation, 

including new realizations of quantized transport (charge/spin pumps) may be realized. These advances 

may include spatially separating the generation and detection of entangled states (e.g., teleportation of 

entangled states); applications based on topological behavior (Majorana fermions, non-abelian quantum 

operations); and the fabrication of distributed networks incorporating high-fidelity quantum sensing, 

communication, and computing.

In summary, establishment of the scientific foundations for quantum systems may lead to applications 

such as novel electronics, efficient light harvesting and photovoltaics, and sensors with capabilities orders 

of magnitude beyond current standards. The ability to probe and model phenomena at the ultimate limits

of detection will enable scientists to advance our understanding of fundamental physics such as emergent

phenomena in strongly interacting quantum many-body systems, quantum gravity, fundamental 

symmetries, cosmology, and nuclear science.
1

1. Introduction

From the transistor to the molecular switch, quantum mechanics is at the heart of nearly all materials 

properties and chemical processes. Still, the subtleties of quantum behavior are often hidden from view. 

As a result, only a small number of scientific techniques and technological applications take advantage of 

the unique phenomena of quantum superposition and entanglement. Harnessing these counterintuitive 

properties of matter promises to yield revolutionary new approaches to computing, sensing, 

communication, and metrology, as well as far-reaching advances in our understanding of the world 

around us. 

The term “quantum systems” (QS) is used in this report to describe assemblies of materials or 

arrangements of trapped ions or electrons in which the uniquely quantum interactions between the 

components are tuned to produce a specific behavior. These systems can be used to process or exchange 

quantum information, or to measure their environment with exquisite sensitivity. The most prominent 

element of such systems is quantum bits—or qubits—which are the basic units of quantum information. 

Qubits are the building blocks of quantum computers, which rely on both superposition and entanglement 

to encode and process information beyond the limitations of the 0s and 1s that are allowed in a traditional 

binary computer. The advent of quantum computing promises revolutionary advances in scientific 

calculations of quantum materials and chemical systems, advances in encryption for the secure transfer of 

information, and enhanced resolution in imaging and detection. The development of QS will also 

contribute to areas outside of computing. Control over quantum-coherent states in artificial systems may 

lead to enhanced transduction for novel electronics, efficient light harvesting and photovoltaics, new 

techniques for cosmology and nuclear science, and sensing capabilities that are orders of magnitude 

beyond current standards. These new capabilities will enable scientists to advance fundamental scientific 

goals, such as understanding emergent phenomena in strongly interacting quantum many-body systems, 

simulating complex chemical and biochemical reactions, probing quantum gravity, detecting dark matter 

and dark energy in cosmology, and understanding the fundamental symmetries of our universe.

However, implementing quantum information science (QIS) remains a significant challenge for the 

scientific community, on both the conceptual and practical levels. Conceptually, we need to learn how to 

allow QS to interact and ultimately transfer information to their classical environments without interfering 

with their quantum coherence—a delicate property that is needed to maintain entanglement and 

superposition. For sensing and detection, we need to learn how to tune QS to maximize their response to 

the relevant external parameters. On a practical level, we need to learn how to create the necessary 

materials, devices, and chemical systems with the exquisite precision needed to achieve long coherence 

times and entanglement. This challenge requires a new understanding of what types of defects are allowed 

in these systems, and how these defects evolve during the synthesis and fabrication of QS.

To address these questions and identify priority research opportunities (PROs), the Department of Energy 

(DOE) Office of Basic Energy Sciences (BES) convened a roundtable of experts in quantum materials 

and QS encompassing physics, chemistry, materials synthesis science, device engineering, detector 

technology, and atomic-scale characterization techniques. This group of experimentalists and theorists 

convened on October 30–31, 2017, to explore the specific opportunities in this rapidly moving field in 

which BES-funded research can play a key role in advancing or utilizing QIS. The goal of this roundtable 

was to define the unique BES roles in this active research field and to provide input on future directions, 

forming the basis for a coordinated, long-term research effort that will enable advances in quantum-based 

science and technology. BES expertise brings unique technical diversity to this area through the materials 

and chemical sciences and world-class user facilities. The participants’ discussions built upon the report 

of a previous Basic Research Needs Workshop on Quantum Materials.

1 But they went beyond the needs 

of quantum materials and also focused on systems, mesoscale assemblies, and materials and chemistry for 

future devices. In particular, the participants were asked to address the following topics:
2

Opportunities to advance the scientific understanding that will enable QIS

• Use or control topological phenomena, quantum entanglement, and coherence 

• Explore scientific phenomena that go beyond stand-alone quantum materials to understand and control 

mesoscale structures and properties

• Create theoretical and computational strategies, drawing upon perspectives from chemical and 

materials science, to design and integrate novel materials for QS

Opportunities to advance instrumentation for the study of QIS, and 

instrumentation based on QIS approaches

• Develop innovative instrumentation for the synthesis, fabrication, and characterization of quantum 

structures and phenomena

• Incorporate quantum phenomena into new characterization probes for materials and chemistry 

research, including quantum-based detectors for neutron, photon, and electron-based instruments

This report summarizes the basic research challenges for both science and instrumentation. The 

roundtable participants identified four PROs, each described in a detailed chapter of this report:

1. Advance artificial quantum-coherent systems with unprecedented functionality for QIS

2. Enhance creation and control of coherence in quantum systems

3. Discover novel approaches for quantum-to-quantum transduction

4. Implement new quantum methods for advanced sensing and process control

Successfully addressing these challenges will enable the creation of coherent QS with unprecedented 

performance for applications in QIS. Doing so requires creating metrics and design rules for quantumcoherent materials and novel material platforms, possibly discovered through the rapid survey of 

robotically synthesized structures, and it will lead to new insight into the physical sciences based on 

ultrasensitive custom sensors. 

When a next generation of quantum-coherent materials is established, large-scale quantum 

manipulation—including new realizations of quantized transport (charge/spin pumps)—may be realized. 

This may include spatially separating the generation and detection of entangled states (e.g., teleportation 

of entangled states); applications based on topological behavior (Majorana fermions, non-abelian 

quantum operations); and the fabrication of distributed networks incorporating high-fidelity quantum 

sensing, communication, and computing. The creation of these systems may lead to novel electronics, 

efficient light harvesting and photovoltaics, advances in cosmology and nuclear science, and an ability to 

achieve sensing capabilities unimaginable by current methods. Such sensing capabilities will enable 

scientists to probe fundamental physics, such as understanding emergent phenomena in strongly 

interacting quantum many-body systems, quantum gravity, and fundamental physical symmetries.
3

Sidebar: Quantum Computers as an Example of Quantum Systems

Optical micrograph of an eight-qubit superconducting processor with a 

ring-type circuit topology. | Image courtesy of Quantum Nanoelectronics 

Laboratory, University of California–Berkeley

Quantum computers are rapidly transitioning from an intellectual curiosity to a 

technological reality. These machines (in which information is stored and manipulated as 

a superposition of different values) can already calculate the properties of simple 

molecules, and they will soon be capable of performing calculations that are currently 

unimaginable—even with the most powerful supercomputers. Such an unprecedented 

advance in computing would enable simulation of the exact quantum mechanical 

behavior of complex molecules, leading to new chemicals and medicines by untangling 

the complexity of molecular and chemical interactions. Quantum computing could also 

enable unprecedented solutions for logistics and supply chains, risk modeling, and 

machine learning. Superconductors are an attractive platform for quantum information 

processing (QIP), as they not only conduct electricity without loss but also allow electrons 

to be entangled “in pairs.” However, a functional device needs many additional 

elements, including tunnel junctions, dielectric sections, and wiring. These additional 

materials, surfaces, and interfaces may be covered with unintentional amorphous layers 

and introduce microwave losses. They may also reduce the coherence of the system with 

excess numbers of quasiparticles, coupling to microscopic electronic defects, or spurious 

phonon modes. In these assemblies of superconducting qubits, developing pristine thinfilm materials that mimic the bulk material is key for QIP. 

5

2. Priority Research Opportunities

PRO 1: Advance Artificial Quantum-Coherent Systems with Unprecedented 

Functionality for QIS

Contributors: Amir Yacoby, Peter Denes, Danna Freedman, Giulia Galli, Stephen Jesse, Chris Palmstrom, 

Nitin Samarth, and Darrell Schlom

What would it take to create materials with pre-designed characteristics optimally suited for QIS?

Consider, for example, a material that can host quantum bits for quantum computation. The bits created in 

such a material would require ultra-long coherence times suggestive of extremely weak interactions with 

the underlying lattice. Conversely, a material designated for quantum sensing would require extreme 

sensitivity to a particular physical quantity and simultaneous insensitivity to all other quantities. Beyond 

the active components, realizing complete integrated quantum hardware necessitates control and 

feedback, with specific design criteria for every class of materials that enable direct integration with 

peripheral components. 

This PRO explores approaches to synthesize QS

ideally suited for targeted applications in QIS. While 

many synthesis apparatuses already incorporate in 

situ characterization, those methods are geared 

toward materials properties, as opposed to QS

performance. Achieving the goal of synthesizing the 

appropriate QS requires adding another key element 

within the synthesis feedback loop that provides 

real-time information on the specific property being 

optimized (Figure 1). Conceptually, at the materials 

level, implementing this idea requires a modular 

setup consisting of synthesis with in situ fabrication,

as well as characterization and theoretical 

capabilities to determine the underlying quantumcoherent properties of the material during both 

synthesis and integration. On the system level, 

modular material components are needed that can be 

integrated and interfaced with the corresponding control electronics and optics. Such a cycle, executed

with rapid turnaround, could generate sufficient data for integration with microscopic theoretical 

prediction and machine learning techniques to iteratively guide the next synthesis and fabrication steps,

enabling rapid convergence. 

Materials, Theory and Instrumentation, Challenges, and Proposed Approaches 

The realization of frontier materials for quantum information will require a nexus between multiple 

innovative strategies—including the assembly of atomically precise material modules and instrumentation 

modules that seamlessly integrate in situ fabrication and characterization, as well as theory and 

computation, in a closed loop. The materials synthesis community provides a foundation to build from, 

with extensive expertise in integrated interdisciplinary approaches to materials synthesis. For instance, 

ultra–high-vacuum techniques like molecular beam epitaxy (MBE) have commonly been combined with 

surface science probes such as scanning tunneling microscopy and angle-resolved photoemission 

spectroscopy to rapidly advance the state of the art in new families of materials including topological 

insulators and novel superconductors.2,3 Similarly, chemical vapor deposition (CVD) techniques have 

been merged with in situ optical characterization and, more recently, x-ray diffraction.4 Despite their 

Figure 1. Creation and study of quantum systems 

focused into a real-time feedback cycle. | Image 

courtesy of Danna Freedman, Northwestern University
6

success, these traditional approaches have significant limitations for the development of QS. First, realtime feedback between synthesis and characterization at the nanoscale is rare, and attempts to directly 

incorporate theoretical input into this feedback loop are scarce. The development of innovative techniques 

that provide atomic-scale characterization during synthesis will enable the incorporation of both 

theoretically directed and machine learning strategies for quickly homing into the optimal window of 

parameter space for achieving desired materials properties. Second, the conventional approach to 

sophisticated materials synthesis of hybrid modular materials imposes severe constraints on the range of 

materials that can be explored with a given system. For example, in a given MBE or metal-organic CVD 

system, changing the materials being synthesized requires expensive modifications. A key challenge and 

opportunity thus presents itself in this context: How can we develop a fast, iterative synthesis technology 

that integrates in situ fabrication and characterization and is informed and/or directed by first principles 

theory and machine learning, thereby enabling rapid convergence toward a desired quantum-coherent 

property.

This challenge can be addressed by numerous synthetic modular approaches to create systems well suited 

for QIS. This section describes four research opportunities. 

1. Robotic synthesis of layered materials

Layered materials, also known as van der Waals materials, offer a unique level of modularity that can be 

harnessed for goal-oriented synthesis, with particular advantages with regard to the metrics inherent to 

QIS.

5 For example, hybrid structures consisting of superconductors and semiconductors can be assembled 

together to host topological qubits.6 Moreover, atomic defects in certain layered materials can serve as 

single photon emitters and possibly even as qubits that can be integrated and interfaced with other layers 

that host the relevant control electronics and optics.

7 Despite the weak interactions between layers, 

stacking disparate materials engenders properties distinct from those of the constituent materials. This 

phenomenon enables us to access a vast phase space for realizing quantum environments that are uniquely 

tailored for QIS.

Unlike bulk material growth, which requires deep knowledge of material compatibility chemically, 

structurally, and energetically, assembly of disparate layered materials offers a pathway to create any 

conceivable material interface. Layered materials open up exciting and rich new possibilities for material 

synthesis that is removed from many of the constraints that exist in traditional growth. Physics at the 

forefront of our understanding of matter exists within layered materials, as low-dimensional materials 

confer a stunning diversity of properties, including semiconducting, superconducting, magnetic, 

insulating, and strongly correlated properties. Some of the emergent physics displayed by layered 

materials include exciting examples such as high-temperature superconductors (BSCCO),8 candidate 

quantum spin liquids (RuCl3),9 topological insulators (Bi2Se3, WTe2),10,11 low-dimensional ferromagnets 

(CrI3),12 and antiferromagnets (FePS3).13 Work in this area will explore new materials that can host 

controllable quantum-coherent degrees of freedom and optimize their performance and integration.

Similar to MBE, robotic synthesis can place one, two, or more monolayers controllably and can even 

control the angle between the layers. This unusually precise structural control confers profound effects on 

the resulting material properties. Key to integrating with QS, the inherent thinness of layered materials 

enables significant light/matter interactions that may be used for manipulating quantum information. 

Coupling these novel states of matter to one another, with extreme control over structure, will open up 

new possibilities for materials discovery and for realizing materials ideally suited for QIS. 
7

Combined with rapid and automated 

assembly, layered materials will allow for 

the creation of stacks with integrated and 

in situ characterization, control, and 

possible integration with silicon 

microprocessor chip technology

(Figure 2). These features will ultimately 

reduce instrumentation costs, because key

components such as electronic amplifiers 

and sources, as well as light sources and 

detectors, can be easily integrated onto 

chips. Fast turnaround times from a 

theoretical material concept to an 

assembled and characterized quantum 

system will enable the accumulation of

huge quantities of data related to the 

quantum properties of such materials and 

their relation to the underlying structure. 

For theory to inform experiments on 

specific pathways and desired materials 

properties, a framework should be 

developed to seamlessly integrate first 

principles calculations for predicting the 

electronic properties of 2D layered materials, with ab initio computations of coherence spectroscopic 

signatures. The large data sets generated will be ideal for machine learning techniques that can predict 

and speed up the discovery of new quantum bits and quantum sensors with optimized coherence ideally 

suited for QIS applications.

2. Incorporating qubits into metal-organic hybrids and interfacing them

Bottom-up assembly of QIP systems consisting of precisely spaced molecular-based qubits provides an 

alternate pathway to the next generation of QIP. A chemical approach to the synthesis of metal-organic 

hybrid qubits benefits from the combination of 

reproducible qubit fabrication, the extraordinary 

programmability and tunability of the qubits by 

chemical design, and the ability to order qubit 

monomers into large-scale arrays through the 

creation of coordination materials (Figure 3).

14

These capabilities enable thinking beyond 

traditional fabrication techniques for the creation of 

3D architectures, as well as the creation of 2D arrays 

amenable to integration with established 

technologies.15,16 Within this approach, molecular 

systems can be studied, assembled into multi-qubit 

architectures, and ultimately integrated into systems. 

The versatility of metal-organic hybrid materials 

provides two distinct, powerful approaches to 

creating new QIP systems. One of these approaches 

focuses on integrating metal-organic systems 

employing those approaches with the device 

technology detailed in the previous section. The 

Figure 2. Design of layered materials through robotic 

assembly and their ultimate incorporation into complete 

systems. | Image courtesy of Oak Ridge National Laboratory

Figure 3. Coordination compounds as viable 

qubits. Three potential applications of 

coordination compound qubits, where precise 

synthetic control enables sensing and computing 

applications. | Image courtesy of Danna Freedman, 

Northwestern University
8

initial step within this approach is interfacing metal-organic hybrid systems with functionalized surfaces, 

as depicted in Figure 4. Integrating qubits onto surfaces will enable rapid feedback regarding qubit 

performance, as described above. A second, more chemically demanding pathway focuses on 

engendering optical addressability within electronic spin-based qubits. The distinct steps required to 

enable these two manifestations of QIP are outlined below. 

Approaching this challenge requires not only the 

rational design of metal-organic hybrid qubits 

with long-lived coherence times17 but also their

assembly into larger architectures. There are 

three crucial challenges to surmount with regard 

to coordination chemistry–based quantum 

computing: (1) single molecule addressability, 

(2) realizing gates to control coupling between 

two or multiple qubits, and (3) integrating metalorganic qubits into larger systems through 

coupling with surfaces and/or light. 

Creating systems incorporating metal-organic 

hybrid qubits has two prerequisites: 

demonstrating single-molecule control over a 

qubit, and establishing two-qubit and multi-qubit interactions. Careful design of molecules displaying 

long coherence times and their subsequent integration into devices will require an interdisciplinary effort, 

bridging materials synthesis, system fabrication, and read-out control.18,19,20 Demonstrating this proof of 

concept will not only achieve qubit control on the atomic scale but also enable scaling of molecular 

systems. A second crucial challenge is demonstrating gate operations within long-lived qubits and 

determining the parameters required for their operation. The initial challenges in this field are the 

construction of a vast library of coupled qubit systems and, from these systems, designing optimal interqubit coupling.21,22 Employing a mononuclear building unit paradigm for creating multi-qubit systems 

could lead to a dramatic increase in the coherence time of the constituent qubits.23,24

Once they are synthesized and characterized, the next key step is integrating 2D metal-organic hybrid 

materials with other low-dimensional materials to create designer QIP systems. The initial steps are 

assembling 2D metal-organic hybrids on surfaces and functionalizing those surfaces.25 These steps can be 

performed in conjunction with the approaches described in the previous section. An alternate approach is 

creating optically addressable qubits from hybrid metal-organic systems. In that case, it is possible to 

harness the tunability of coordination compounds to engineer the ideal optical properties. Coordination 

compounds offer the additional advantage of precise qubit positioning, thereby enabling the synthesis of 

arrays of optically addressable qubits. These qubits could then be integrated into larger constructs.

3. Endowing new materials with desired topological properties

In virtually all implementations to date of QS, one of the states is an excited state that must, of necessity, 

decay spontaneously into its ground state. This decoherence quickly destroys the quantum calculation and 

is one of the most significant challenges facing QIS. A fascinating alternative form has been proposed: 

braiding pairs of ground-state non-abelian anyons in two dimensions.26,27 Importantly, an anyon is not an 

excited state and so does not suffer decoherence, preserving quantum information ad infinitum. By 

avoiding decoherence, QIS calculations can continue for a much longer time using this approach. In 

principle, one of the simplest ways to create and use pairs of such anyons occurs in odd-parity 

superconductors; p-wave, f-wave, and so on, can be topological and, according to theory, would all 

support a bound E = 0 quasiparticle state.28 When localized in real space, this bound E = 0 state is dubbed 

Figure 4. Schematic of metal-organic hybrid system 

integrated with a surface. | Image courtesy of Danna 

Freedman, Northwestern University
9

the “Majorana zero-mode” (MZM); the MZM is its own antiparticle, and the braid group of MZM is nonabelian. 

Over the past decades, several promising candidates for such odd-parity topological superconductors 

(OPTSs) have been identified; yet clear and convincing evidence for any system remains to be 

established. These enabling materials are of paramount importance to the future of QIS, and if such 

materials can be found,29,30 they will readily be implemented in QIS device architectures that are already 

worked out. Thus, research to develop OPTSs and to establish that they indeed harbor MZMs and are 

capable of non-abelian quantum operations is highly promising.

One strategy is to develop an OPTS that can be deposited as a 2D sheet over large-area wafers. This 

approach has the advantage of scalability and would provide a robust platform for the study of groundstate non-abelian anyons in two dimensions. Such wafers could be patterned into thousands of anyonic 

qubits and thereby lay the practical foundation for anyonic ground-state QIS. The leading single-phase 

OPTS is Sr2RuO4,

31 but compelling evidence for its odd-parity superconductivity remains elusive.32

Superconducting thin films of Sr2RuO4 were recently synthesized,

33,34 and strain appears to be a 

promising way to significantly increase their superconducting transition temperature (Tc) from the 1.5 K 

of unstrained Sr2RuO4.

35,36,37 A higher Tc pushes the excited states of the system to higher energies, which 

is beneficial for ground-state quantum computing, in which it is desirable to braid ground states and 

operate under conditions that minimize contributions from excited states. A higher Tc also means a larger 

superconducting gap ∆, making it easier to establish whether a material is an OPTS. Materials-specific 

embodiments of OPTS at interfaces are being predicted and are an exciting area for materials 

discovery.38,39

Another strategy is to follow the proposal by Fu and Kane to create an OPTS at the interface between a 

topological insulator and an s-wave superconductor.40 Sau et al.41 predicted that a conventional 

semiconductor, in which s-wave superconductivity and Zeeman splitting are induced by the proximity 

effect, would also support MZMs. Signatures of zero bias peaks (ZBP) in differential conductance data 

consistent with MZM were first reported for InSb semiconducting nanowires with a NbTiN 

superconductor contact.42 Replacing NbTiN with epitaxial aluminum as the superconductor, combined 

with recent advancements in fabrication and processing, has yielded hard superconducting gaps43

(enduring up to B ≈ 0.9T) and substantial improvement in the ZBP, reaching close to the theoretical 

predicted value of 2e2

/h.44 One of the key challenges of the nanowire approach is that it requires fine 

tuning of the chemical potential and magnetic field to reach the topological phase. Additionally, its 1D 

nature poses severe challenges in scalability. Recently, there have been several proposals for realizing 

induced topological superconductivity with MZM using 2D architectures45 that do not require fine tuning 

and have the potential for scalability.

46 Such 2D approaches are also implementable using the layered 

approach described in the earlier section on robotic synthesis. 

4. Precise positioning of atomic defects 

Direct manipulation of individual atoms in matter at the atomic scale is a recent and revolutionary 

technology.47,48 Scanning probe and electron microscopes are being reinvented to not only image the 

structure and function of materials with atomic resolution but also modify materials at the fundamental 

level.49,50 These emerging capabilities open new pathways for imbuing solid-state systems with quantum 

functionality by enabling direct fabrication and editing of local structure and chemistry. The controlled 

introduction and manipulation of complex defect systems, combined with atomic-scale measurements of 

quantum behavior, provide a fast and tight feedback loop to accelerate research in QIS via real-time 

interaction with the basic building blocks of matter.51
10

The advent of capabilities to address single atomic sites, and the ability to position atomic-scale defects,

offer promise for the creation and manipulation of novel atomic defect–based QS. It is notable that even 

for very well-known materials such as diamond or SiC, new defects with unique coherent properties 

continue to be discovered, suggesting that the phase space for defect-derived quantum functionality is 

truly vast.52,53 In such cases, though, progress depends on natural random processes for defect creation 

and serendipity in their discovery. Alternatively, local manipulation and measurement of matter allows 

for the construction of complex defect ensembles and the ability to study these ensembles by 

systematically varying, for instance, bond conformation, spacing between dopants, or dopant types. The 

variation enables a direct understanding of the correlations between non-quantum observables, such as 

structure, with specific quantum behaviors. This approach is being successfully employed to realize spin 

qubits in silicon.

54 Note that it may also be possible to employ this approach in conjunction with the 

bottom-up chemical synthesis for metal-organic hybrids described earlier.

Scanning transmission electron microscopy 

(STEM) offers an emerging path for imaging and 

direct manipulation of atomic structures as well as 

measurement of quantum properties (Figure 5).55

Recent years have seen a proliferation of highresolution STEMs, and their propensity for beaminduced modifications in solids has led several 

groups to observe atomic-level beam-induced 

modifications, including sculpting,

56 crystalamorphous phase transitions,

57 bond creation, 

vacancy creation,

58 directed single-atom doping,59

and controlled dopant motion and arrangement60

within 2D and 3D crystals. The ultimate goal of 

guiding transformations to yield specific final 

designs with desired behavior requires the 

development of advanced feedback and control 

systems based on large-scale data acquisition, and 

advanced machine learning–based processing, 

coupled with theoretical models that capture 

beam-matter interactions and can predict specific 

spectroscopic signatures and coherence times. 

Although final applications necessarily rely on 

macroscopic contacts or optoelectronic 

connections, of interest here is prototyping and 

probing quantum behaviors via microscopybased observables to accelerate the research 

cycle. Further advances in electron energy loss 

spectroscopy (EELS) can be used to chemically 

identify single atoms and map local plasmon and 

phonon behavior. Electronic properties can be 

probed via cathodoluminescence to map local 

densities of states, emitter decoherence 

dynamics, and information about the quantum 

state of a defect with picosecond temporal 

resolution.

61 They can be predicted by first principles calculations based either on density functional 

theory or advanced many-body perturbation theory methods.52

Figure 5. (a) Enhanced STEM enables building and 

editing of atomic assemblies and assessment of their 

quantum properties. (b–e) Directed doping and 

guided motion of dopant through graphene lattice. 

(f–g) Beam-directed atom-by-atom fabrication of 

silicon dimer, trimer, and tetramer. | Reprinted by 

permission from Nature Publishing Group. Nature, Fire up the 

atom forge, S. Kalinin, A. Borisevich, and S. Jesse, copyright 

2016
11

Operating interactively at the fundamental length scale of materials sciences through direct observation 

and control will provide new insight into how and why novel phenomena emerge and will provide new 

pathways for creating and exploiting valuable properties for novel devices for QIS.

Potential Impact 

The overall aim of this program is to create the fundamental scientific and technological understanding to 

develop integrated coherent QS with unprecedented performance for applications in QIS. 

Real-time feedback with atomic-level control of synthesis, based on theoretical predictions and 

measurements of quantum characteristics, will enable rapid development of artificial quantum-coherent 

systems with predesigned functionality for QIS. Development of in situ lithographic processing of 

quantum materials down to the atomic scale will allow for unprecedented control to facilitate the 

fabrication of structures for QS. Integration of in situ techniques to measure quantum properties will 

allow immediate feedback between synthesis and functionality, providing important fundamental 

experimental measurement feedback to theory. Creating and measuring control structures specifically to 

test theoretical predictions is crucial for theory development and will aid the cycle of quantum 

information development. Sculpting and deposition can introduce small-scale topological changes (by 

cutting holes and closing loops) and can be used to locally tune confinement and strain-related properties 

(e.g., local bandgap). Arrays of dopant atoms, or metal-organic sites, with specified arrangements can be 

introduced to create highly tunable superlattices to enhance particular phonon, plasmon, or optical modes. 

By the use of atoms with accessible spin states, atomic-scale magnetic structures or quantum entangled 

arrays can be artificially created and studied. Operating interactively at the fundamental length scale of 

materials science through direct observation and control will provide new insight into how and why novel 

phenomena emerge and will provide new pathways for creating and exploiting valuable properties for 

novel materials and devices, such as ultrasensitive sensors, that will give insight into other fundamental 

areas of science. 

Automation of the synthesis process, combining data-based machine learning and atomistic theory with 

real-time analysis, will allow rapid surveys of materials systems and convergence toward materials with 

desired quantum properties. The large amounts of data created will provide input for developing metrics 

and design rules for quantum-coherent materials and systems. 

13

PRO 2: Enhance Creation and Control of Coherence in Quantum Systems

Contributors: Michael E. Flatté, Darrell Schlom, Irfan Siddiqi, and Toni Taylor

Quantum-coherent systems have exhibited remarkable coherent phenomena,

62–67 including the ever 

increasing coherence times necessary for QIS.

68–70 Even more important than the absolute time scales of 

coherence are the greater than ten orders of magnitude by which coherence times can exceed the intrinsic 

dynamical time scales of such systems.

71 This exceptional ratio of coherence times to evolution times 

suggests extensive regimes of coherent behavior during which complex entangled states can be 

established and evolve before they decay. Our understanding of the complexity of entanglement remains 

limited to the behavior of small numbers of quantum-coherent systems. Advancements in this field will 

come from new understandings of the scaling of coherence lengths and times with system size and 

complexity, from clarifying the distinction and interactions between the quantum-coherent system and its 

surrounding incoherent bath of excitations, and from identifying new signatures of quantum states in 

artificial quantum-coherent systems. The current focus of the field on slow changes in the parameters and 

features of quantum-coherent systems, in order to adiabatically change their properties, will expand to 

scenarios in which fast, non-adiabatic changes can be made that weakly couple to an incoherent bath, if at 

all. Researchers can expect to discover, during these investigations, novel entangled excitations with 

unexpected properties, including surprisingly long coherence times or stable behavior when manipulated. 

This behavior will enable advances in artificial quantum-coherent systems as described in PRO 1.

Specific Challenges and Proposed Approaches

The following four sections discuss specific challenges within this area.

1. Overcoming the tyranny of low temperature

At room temperature, the environment continually exposes QS to excitations with intrinsic dynamical 

time scales of less than 100 femtoseconds.

62,63 This has forced most implementations of QS to operate at 

low temperatures. Nonetheless, quantum states in many quantum-coherent systems overcome this tyranny 

of low temperature and remain impervious to this hot, incoherent background. At the same time, these 

quantum-coherent systems respond dramatically to other perturbations, such as the average temperature 

or fluctuating magnetic fields, which have characteristic time scales of microseconds or longer. Quantumcoherent systems that demonstrate this behavior include color centers in wide-gap semiconductor 

materials, such as the nitrogen vacancy (NV) center; triplet/singlet systems in organic molecules and 

complexes; and unpaired spins in insulating barriers, especially in tunneling transport. 

The resilience of quantum-coherent systems against the hot bath—even as they retain their sensitivity to 

specific types of excitations—is connected to the enforcement of particle statistics, such as the Pauli 

exclusion principle, within a limited set of available states of a small discrete system. A common 

arrangement of states is that orbital and exchange energy scales in excess of an electron volt establish 

selection rules for transitions at energies of much less than 1 eV, including at room temperature

(equivalent to 25 meV). Certain specific perturbations, however, break these selection rules. Thus, a 

perturbation with an energy scale in the micro-electron volts can dramatically influence an observable at 

room temperature (Figure 6). A characteristic feature of such phenomena is the “state bottleneck” in 

which the system attempts to make a transition, is thwarted by the selection rule, and then succeeds, aided 

by the perturbation. Systems far from equilibrium, such as color centers under optical pumping or 

orbitally incoherent transport in organic materials under large electric fields, enhance these bottleneck 

effects.
14

 

Figure 6. (Left) Schematic energy scales for spins when coherence influences dynamical transitions in 

transport, recombination, or reactions. Spin selection rules push other possible states far from accessible 

thermal energies as a result of Coulomb charging or orbital transition energies. | Image courtesy of M. Flatté, 

University of Iowa. Much smaller energies that break these selection rules can manipulate spin-correlated 

dynamics even at room temperature. (Right) Back-action of magnetic fields induced in a sample on an NV 

sensor.

72 |Reprinted figure with permission from J. van Bree and M. E. Flatté, Atomic-scale magnetometry of dynamic 

magnetization, Phys. Rev. Lett. 118, 087601, 2017, copyright 2017 by the American Physical Society

Challenges in understanding these situations persist. They include how to understand the coherent 

evolution of a superposition of quantum states on microsecond time scales, when the bath causes

fluctuations on far shorter time scales that perturb the relative energy of the quantum states in the 

superposition by far more than the coherent evolution rate. Although a theoretical analysis based on a 

limited number of possible quantum states of a bath suggests that the bath fluctuations quench quantum 

coherence, experimentally the quantum coherence survives. Thus, a central challenge remains to 

understand the decoherence of open QS, which appears to be far less rapid than current theories suggest. 

In other scenarios, there is a bath that does couple strongly to the quantum-coherent system under 

exploration. An enduring problem in condensed matter physics is the so-called central spin,

73 which is a 

distinct spin entity that interacts with a bath of excitations with spin character. Examples include the 

evolution of the NV spin (here the central spin, since it is independently measurable) during interaction

with a surrounding bath of electronic spins (e.g., from substitutional nitrogen dopants) and nuclear spins 

(e.g., from nitrogen or carbon nuclei).

74 A related and equally important challenge is to experimentally 

characterize the coupling of quantum-coherent systems to the bath and to better describe the behavior and 

dynamics of the bath. Does it consist of a collection of nearly homogeneous systems—as in a uniform 

spin ensemble, or a heterogeneous assembly of systems with very different coherent properties—such as a 

solid with electron spins of various types, some mobile and some not; nuclear spins; and possibly 

ferromagnetic order.

2. Toward rapid manipulation of quantum-coherent systems

Our simple current pictures of quantum coherence, which appear inadequate to understand the persistence 

of coherence in a hot bath, also motivate researchers to focus on slow manipulations of QS to avoid 

unintended transitions to other quantum states. In an adiabatic transition, to avoid Landau-Zener tunneling 

across the gap, the time of transition, Δt, must be sufficiently long that it exceeds ħ/ΔΔΔΔ, where ΔE is the 

energy gap in the system’s spectrum to other excitations. However, under some conditions, a hot bath 

fails to efficiently drive transitions to other quantum states even in the complete absence of any spectral 

energy gap to these other quantum states. Therefore, it must be recognized that fast, nonequilibrium, 

nonadiabatic changes in the parameters of the quantum system should also be possible that do not 

substantially damage the coherence of these quantum-coherent systems.

75 A new theoretical framework 

for non-adiabatic manipulations of quantum-coherent systems may point the way to highly efficient 
15

changes in the quantum states of certain systems. For example, as a result of the limited set of relevant 

quantum states for an NV center in diamond, researchers have demonstrated extremely fast manipulation 

of its spin state, going beyond the rotating wave approximation for spin resonance (Figure 7). Faster 

manipulation may also assist in the quantum-to-quantum transduction described in PRO 3.

Figure 7. Highly nonadiabatic transitions for a coherent spin center in diamond, showing accurate pictures 

of the complex spin dynamics even though the rotating wave approximation has failed. |From G. D. Fuchs et 

al. Gigahertz dynamics of a strongly driven single quantum spin, Science 326(5959), 1520–1522. Reprinted with permission 

from AAAS. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, 

adapted, performed, displayed, published, or sold in whole or in part, without prior written permission from the publisher.

3. Novel quantum states of quantum-coherent systems require novel probes and new 

theories

Considerable development effort has been devoted to the techniques that can measure individual quanta, 

including single photons, single phonons, single electrons loaded into or out of a quantum dot, or single 

spins. Understanding the nature of and opportunities for coherence in QS involves exploring the 

correlations and entanglements between individual quanta and how they persist, decohere, or otherwise 

evolve in time or over space. The tools available for probing such correlations and entanglements are only 

at an early stage of development. Typical approaches for correlated measurements such as Bell state 

measurements require manipulating the entangled state of the system into a product state before 

performing the measurement. However, the use of multiphoton entangled states as probes permits 

measurement of objects below the Rayleigh refraction limit. Probes producing entangled photons should 

also allow direct measurements of entanglement in electronic systems76 (Figure 8); however, new 

methods of preparing and preserving these quantum states, and of directing them toward materials to be 

measured, must be developed. As the generation of entangled photons typically requires optical 

nonlinearities whose effects improve at high flux, facilities that produce high flux provide unique 

opportunities to implement these novel probes. Measurements of these quantum signatures of quantumcoherent systems require, in the end, conversion to classical information. This requirement identifies the 

challenge of connecting signatures of quantum phenomena to classical signatures as a critical step in 

quantum measurement theory and in the development of successful new probes of quantum-coherent 
16

behavior. These key features, the features required to probe new quantum-coherent behavior, and their 

impact on the fundamental limits to measurement, are explored further in PRO 4.

Figure 8. Schematic configuration for use of entanglement induced in photons to measure entangled 

electronic states, as proposed in Leuenberger et al.73 The third-order correlation measurement with three 

detectors (C3 in Leuenberger et al.) of an entangled state of the spins of three quantum dots, (| ↑↓↓> +| ↓↑↑

>)√2, is shown. One detector responds to left circularly polarized light, one responds to right circularly 

polarized light, and one does not sense polarization. The separation between each polarized detector and 

the unpolarized detector is the same; the pattern is plotted as a function of that separation. | Image courtesy

of the Flatté group, University of Iowa

Along with the exploration of methods to access the behavior of entangled states with outside probes, we 

can expect approaches to manipulate the internal coupling between entangled states of quantum-coherent 

systems in order to enhance or suppress those internal correlations, which can then be measured with 

these new probes. As advances in the theoretical understanding of quantum-coherent systems are made in 

constructing new correlation functions, direct probes of those correlations will provide the best test of 

new theoretical descriptions of coherence. To take advantage of such situations, the bath itself might be 

manipulated to reduce coupling to interesting quantum states in order to allow those correlations and 

entanglements of interest to persist for longer times.

4. Revealing the role of disorder through material control

The complex role of disorder in quantum-coherent phenomena has been anticipated since the earliest 

work on nuclear magnetic resonance, when disordered systems were found to have longer coherence 

times due to motional narrowing. A similar effect lengthens spin coherence times in semiconductor 

materials such as gallium arsenide, whereas disorder shortens spin coherence times in copper and silicon. 

These different effects originate from differing and competing influences of disorder on the spin-orbit 

interaction, when combined with ordinary electronic scattering events in the materials. Control of disorder 

can perhaps be understood, therefore, as a way of manipulating the coupling of the quantum-coherent 

system to the ever-present thermal bath, and of limiting or enhancing the effect of the bath on 

decoherence. Similar effects should occur in more complicated quantum states of quantum-coherent 

systems. Thus the design, simulation, and characterization of new materials with controlled disorder will 
17

offer insight into the nature of coherence in these quantum-coherent systems.

77 Included in this 

opportunity would be the unique design and fabrication of artificial disordered systems, including the 

“defect in an effective crystal” approach that has proved very powerful for photonic and magnonic 

crystals (Figure 9) (discussed in more detail in PRO 1).

Figure 9. (a) A 2D photonic crystal cavity made from a nanodiamond film. (b) GaP microdisk and (c) GaP 

waveguide deposited on single-crystal diamond. (d) Manipulating a nanodiamond hosting a single emitter onto 

a toroidal microresonator using a fiber taper. (e) Nanodiamond hosting a single emitter on a silica microdisk. (f)

Atomic force microscopy image of a diamond nanocrystal placed in a GaP photonic crystal cavity (top) and 

the simulated electric field profile of the cavity's fundamental mode (bottom). |Reprinted by permission from Nature 

Publishing Group. Nature, Diamond photonics, I. Aharonovich, et al. copyright 2011 

Impact: Understanding Coherence in Quantum-Coherent Systems

The simplest coherent properties of quantum-coherent systems have already been enhanced to 

macroscopic time scales and length scales; however, the more robust these systems can be made, the more 

complex and revealing the coherent phenomena they demonstrate. Simple examples of quantum 

manipulation, such as charge and spin pumps, have been demonstrated over short times and short 

distances but are not practical for the precise control of transport. Advances in controlling coherence 

should expand the range of systems in which charge and spin pumps can be constructed, perhaps to 

organic molecules and even to room temperature. Teleportation of simple quantum states has been 

demonstrated in a wide variety of QS, including photons, spins, and atomic excitations. How far can we 

go in teleporting entangled states? At what degree of spatial separation can we generate and detect 

entangled states? Can these be used to illuminate new quantum phenomena? Or to detect very small 

changes in the fabric of space and time, such as those created by gravitational waves? Novel sensing 

modes have emerged from each advance in the control of coherence, from magnetic resonance imaging to 

precise, local sensing of temperature in liquids. 

Novel manipulation of coherent systems is planned for QIP, which poses challenges in the size and number 

of the quantum-coherent systems to be connected together. Some robust proposed forms of quantum 

computation require manipulation of the parameters of a gapped system that has unique topological 

properties under parametric control. The opportunities identified here suggest that, based on the properties 

of some quantum-coherent systems, the nature of a system’s energy gap need not be so complete, or perhaps 
18

the manipulation of parameters need not be as slow, as currently anticipated. However, when considering 

the behavior of these unusual excitations, and how they behave when braided together, we simply do not 

have a solid description yet of how that phenomenon can be observed. How can these excitations be 

uniquely identified? How is braiding itself to be measured? For a specific system of interest, what is the best 

way to characterize and quantify entanglement, as practicalities may limit access to the ideal experimental 

observables? Only by building a thorough understanding of creating, controlling, and transporting coherence 

in quantum-coherent systems can we address these fundamental questions. 
19

PRO 3: Discover Novel Approaches for Quantum-to-Quantum Transduction

Contributors: Irfan Siddiqi, William Oliver, and Birgitta Whaley

At the core of quantum measurement and information processing is the transduction of information from 

one physical modality to another at the single quantum level. Such processes span the simple detection 

and recording of the number of quanta in an input signal, such as in a photon counter, to the full transfer 

of the quantum wavefunction implicit in some quantum repeaters needed for the long-distance 

transmission of quantum signals. Furthermore, hybrid-QS78 that distribute detection, storage, and 

processor functionality into different physical architectures rely on efficient transduction between 

different parts of a complex material system or between constructed heterosystems with well-defined 

interfaces. An example of such a hybrid is a doped semiconductor in which a long-lived, isolated system, 

such as a nuclear spin bath, is used as a memory element in combination with more interactive electron 

spins suitable for gate-based logic operations. Experimental and theoretical directions in quantum 

transduction include developing schemes to encode and decode quantum information across different

physical systems, elucidating quantum and statistical mechanical limits to sensitivity, and optimizing 

materials to suppress decoherence—and thereby harnessing quantum effects that include entanglement for 

information processing.

Scientific, Instrumentation, and Computational Challenges and Opportunities

A grand challenge in QIS is the generation and stabilization of quantum states in a variety of different 

materials systems. QIS holds the promise of superclassical performance in information processing and 

communication. To realize this promise, quantum coherent states must be realized and maintained in 

physical systems. Although local systems constitute a processor, it is advantageous to additionally 

distribute this quantum information across multiple nodes. Whereas one materials system may be well 

suited to a given task, it is likely that multiple coherent systems will be used to sense, process, and 

distribute quantum information. Examples of such objects include nonclassical states of light and 

matter—including Fock and squeezed states, as well as superposed and entangled combinations of 

electronic, magnetic, and vibrational degrees of freedom. Additionally, efficient quantum-state 

transduction relies on the identification of materials systems and associated control protocols that allow 

coupling to these quantum signals without directly inducing decoherence or resulting in an additional 

susceptibility to noise. Moreover, decoherence from imperfections at materials interfaces and in the bulk 

needs to be mitigated in conjunction with a deep understanding of noise—both in isolation and coupled to 

a bath—to generate the precursors for high-fidelity quantum devices. Near-term opportunities include (1) 

the detection of single quanta in key photon frequency bands, single magnons, individual spin dynamics

and excitations in magnetic materials, and individual lattice vibrations; (2) the efficient transmission of 

quantum information; and (3) the development of functional interfaces for energy conversion and 

harvesting.

1. Quantum state replication

Quantum communication enables enhanced security against eavesdropping attacks by using nonclassical 

states of light—e.g., single-photon states or two-photon entangled states—to encode and decode a 

transmitted message.

79 There are three primary challenges to realizing practical quantum communication. 

First, the generation of the nonclassical states of light is generally stochastic and low in fidelity. Second, 

in modern optical fiber or free-space communication, there is distributed loss that limits the 

communication distance to on the order of 1200 km.80 Third, the no-cloning theorem of quantum 

mechanics forbids the duplication of a quantum state and is a foundation for the security of these 

protocols. While this theorem prevents an eavesdropper from copying a message in transit without 

detectably altering the measurement outcomes, it also prevents the intentional reconditioning of the 

quantum states over large distances.
20

A quantum version of an optical repeater, a quantum repeater, enables long-distance quantum 

communication by addressing these limitations.

81 A quantum repeater is a local quantum memory 

(potentially with local error correction) that stores distributed entanglement at several nodes along the 

communication channel. Nonclassical light is generated at each node in the link and shared with adjacent 

nodes, whereby teleportation is used to distribute the entanglement across multiple nodes that make up the 

link. Because the generation is stochastic and, at least currently, of limited quantum efficiency, each node 

must also have a quantum memory to preserve the local entanglement while the entire link is being 

established. Quantum communication would benefit from the development of on-demand, high-efficiency 

sources of nonclassical light, the development of long-lived quantum memories, and the advent of 

quantum error correction to maintain the memory.

2. Microwave single photon detectors

Whereas the most advanced solid-state information processors to date all operate in the microwave 

regime, the ability to route and detect microwave photons on-chip is currently limited compared with

similar technology operating in the optical domain.

82 Current microwave single photon detectors can 

broadly be divided into three categories: (1) event detectors that operate continuously in time and attempt 

to accurately record the arrival time of a photon, (2) time-gated devices by which a photon can be 

detected with high efficiency only if accurate information about the arrival time is given, and (3) 

frequency-selective detectors that can detect photons within a certain bandwidth. Not only are very high 

quantum efficiency and low dark count rate required for most applications; an efficient photon counter 

also requires fast measurement; large bandwidth; short dead times; low timing jitter; and, in certain 

applications, spectral resolution. Depending on the application, the ability to resolve photon numbers is 

also desirable, as well as photon detectors that are nondestructive, i.e. that do not destroy the photon in the 

detection process. 

Although some of the theoretical proposals and proof-of-principle experiments have reported progress on 

some of the mentioned metrics, no proposal has been put forth yet that convincingly performs well across 

all specifications needed. In particular, many detectors that promise high quantum efficiency suffer from 

narrow bandwidth and long detection times. Others impose technical constraints not easily dealt with 

experimentally, such as the need for multiple cascaded circulators, which are currently bulky and lossy.

The development of these supporting quantum microwave components—e.g., isolators, circulators, 

diplexers, mixers, and beam splitters working in the quantum domain—will have a large impact both for 

quantum computing and in the broader field of quantum control and measurement. Single photon 

detection in this domain and into the mid-infrared has many sensing applications as well, including dark 

matter detection in cosmology.

3. Light to electron transduction: Light harvesting in photosynthesis

The light harvesting apparatus of plants and bacteria possesses remarkable capabilities of reaching near 

unit efficiency for the conversion of an absorbed photon to an electron, which goes on to initiate the 

“dark” or chemical reactions of photosynthesis.83,84 This is an example of transduction of excitonic energy 

to electron current (Figure 10) in a natural setting that is highly efficient, unusually so for a biological 

system, with quantum efficiencies for the conversion reaching 95–99% under weak light conditions. It is 

also extremely robust against changing conditions: the photosynthetic apparatus possesses a highly 

sophisticated chemical sensing and feedback mechanism that shuts down the critical conversion step 

when the plant is saturated with light, to avoid overproduction of electrons and consequent photo-damage. 

Recent ultrafast spectroscopy and theoretical work have revealed insight into the quantum dynamics of 

the energy transfer and show how the excitonic degrees of freedom interact cooperatively with phonons to 

ensure the optimality and robustness of the transport in the presence of disorder. This approach can 

provide important insights for the design of quantum-to-quantum transducers. However, the process of 

photon absorption in light-harvesting systems is not very efficient and renders the overall efficiency of 
21

generating electrons from incident photons much lower than the internal quantum efficiency. To enable 

single photon counting experiments that correlate absorbed and fluorescent photons on time scales shorter 

than nanoseconds, it is essential to develop robust heralded single photon sources in the 600–700 nm 

regime relevant to electronic absorption by chlorophylls and other photosynthetic pigments, fast 

(picosecond) photon detectors, and improved time resolution correlators. Such studies can play a valuable 

role in elucidating the spatio-temporal correlations among the multiple absorption events necessary for 

light-harvesting systems (e.g., for Photosystem II in green plants) to absorb the full energy equivalent of a 

single photon, which is required for transduction of the excitonic energy to an electron-hole pair and thus 

to a discrete electron.

Figure 10. The light-harvesting apparatus of green sulfur bacteria and the Fenna-Matthews-Olson (FMO)

protein. The schematic on the left illustrates the absorption of light by the chlorosome antenna and 

transport of the resulting excitation to the reaction center through the FMO protein. On the right is an 

image of a monomer of the FMO protein, showing also its orientation relative to the antenna and the 

reaction center. The multi-ring units are BChla molecules and the surrounding β sheets and α helices form 

the protein environment in which the BChla molecules are embedded. | Reprinted by permission from Nature 

Publishing Group. Nature Physics, Quantum entanglement in photo-synthetic light-harvest complexes, M. Sarovar, et al. 

copyright 2010

4. Maximizing coherence at quantum interfaces

There is a general consensus within the research community that understanding and further mitigating 

sources of decoherence in condensed matter systems (Figure 11) is critical to the development of more 

advanced applications. Coherence times should be made as long as possible, as exceeding the thresholds 

for quantum error correction will considerably reduce redundant resource requirements. Both energy

relaxation and pure dephasing times, T1 and Tφ, are related to the environmental noise seen by the qubit, 

as characterized by a spectral density, S(f), and much is known about this noise.

84,85 For example, 

inhomogeneous dephasing arises from broadband, low-frequency (e.g., 1/ f -type) noise in the charge, 

spin, and critical current. However, although it is consistent with a bath of two-level fluctuators (or 

clusters of fluctuators), its precise microscopic origin is still being investigated.

86,87 Energy relaxation 

occurs as a result of noise at the qubit frequency, and design modifications can change the device 
22

sensitivity to this noise in ways that are understood. However, although several mechanisms are known to 

exist (e.g., coupling to microscopic defects), their origin is not well understood. Mitigating these types of 

decoherence mechanisms ultimately reduces to two general approaches:

1. Reducing sensitivity to a given type of noise through design modifications

2. Identifying and mitigating noise sources through materials/fabrication improvements 

Figure 11. Illustration of various decoherence mechanisms that can affect superconducting qubits. The 

mechanisms include those related to materials and fabrication, as well as design and packaging 

considerations (environmental circuit modes and photons). | Image from W. D. Oliver and P. B. Welander, 

Materials in superconducting quantum bits, MRS Bulletin 38(10), 816–825, 2013, copyright 2013 by Cambridge Core.

Reproduced with permission

In practice, the coherence improvements over the past decade were made through a combination of 

improved designs, improved fabrication, and improved materials.88 From this perspective, there remains 

an important role for materials and fabrication research to further improve qubit coherence times, with 

regard to both identifying new noise mechanisms and incorporating novel materials that, for example 

using topological effects, can exhibit immunity to sources of imperfection.
23

5. Theory of quantum state transfer

A key challenge in any quantum transduction scheme is to find a quantum system that is flexible enough 

to couple strongly and coherently to a variety of distinct systems and is thus capable of acting as a 

“quantum bus.” In many cases, systems that have this requisite flexibility are themselves more susceptible 

to loss and noise. A prime example is the use of vibrational modes of a mechanical resonator as a 

quantum bus, as has been recently realized in optomechanical systems attempting the coherent conversion 

of optical photons to microwave photons (see, e.g., Andrews et al. 201489). The large laser powers used to 

achieve strong coupling in these systems naturally lead to heating in the mechanical mode. For standard 

sequential transfer protocols, this heating then corrupts any desired quantum state transfer. One ideally 

would like a transfer protocol that allows the effective coupling mediated by such a noisy quantum bus to 

be used without being affected by any associated noise or loss. Adiabatic state transfer schemes (such as 

STIRAP90) provide a potential solution but have extremely slow protocol times. A key theoretical goal is 

thus to find methods to accelerate such protocols in such a way that the protection of the adiabatic scheme 

remains without the extremely long time scales required for adiabatic evolution. A variety of approaches 

to this very general problem in quantum dynamics have been suggested (so-called “shortcuts to 

adiabaticity”

91), but their application to quantum state transfer is only in its infancy: current approaches 

are limited to systems with a limited number of degrees of freedom and do not fully account for quantum 

dissipative effects.

92 The development of shortcuts to adiabaticity for quantum state transfer in realistic 

settings will have a dramatic impact on the variety of systems capable of acting as quantum buses and 

could also lead to new general insights into quantum dynamics.

6. Thermodynamics of quantum machines

QIS provides the tools to understand and to probe the interactions of quantum systems with their 

environments. In building and controlling quantum devices—whether these are computers, repeaters for 

communication, or sensors—issues of energy and power efficiency and heat transfer arise. They raise 

fundamental questions about the nature of thermodynamics in the quantum regime and at the nanoscale;

i.e., how should quantum thermodynamics be analyzed and how does it help in the quest to build and 

operate quantum devices in an open environment where work, heat, and even particles may be 

exchanged?

Understanding and exploiting quantum measurements of variable strength is a key component of the 

opportunity to explore how thermodynamic quantities such as work and heat are affected by quantum 

correlations, fluctuations, and coherences.93 Monitoring in an interaction-free limit will be a valuable and 

possibly essential component of validating quantum state transfer between two quantum systems—i.e., 

quantifying the fidelity of a quantum-to-quantum transduction process under non-ideal conditions. The 

practical implications of doing so are general, affecting all quantum devices that operate with some 

degree of coherence. Some key questions are

• How can we construct a coherent engine and optimize its efficiency and power output?94

• Can we construct and operate a single-atom engine?95

• How do we describe and probe heat management for quantum devices?

• What are the trade-offs between speed of operation and accuracy of outcome?

Classical thermodynamics says that faster processes are generally less efficient. This rule is often 

summarized by fluctuation theorems that relate fluctuations in response to external forces to the 

irreversible work. How do the corresponding quantum fluctuation relations constrain the behavior of real 

quantum devices—both atomic-scale, as in trapped atoms and ions, and macroscopic, as in 

superconducting qubits? How do nanoscale quantum devices thermalize, and how may this reaction be 

controlled? The design and optimization of nanoscale and mesoscale thermal devices, such as atomic-
24

scale refrigerators for quantum simulations with atoms and ions, and artificial light harvesting devices,

force us to analyze the functioning of open quantum systems in thermodynamic terms.

7. Quantum mechanical systems and transduction

Quantum coherent behavior can be supported in many distinct forms of matter and light. Such systems 

can be prepared in well-defined quantum states, and range from the microscopic to the macroscopic; they 

also bridge the traditional divides among condensed matter, quantum optics, and atomic physics. New 

functionalities can be achieved by combining these quantum mechanical building blocks in 

heterostructures involving quantum-to-quantum transduction. Examples of candidate quantum primitives 

include, on the microscopic side, spins in semiconductors (both nuclear and electronic), where coherent 

control has been used to prepare entangled states and perform basic quantum operations. These include 

defect spins (e.g., NV centers in diamond) as well as gate-defined quantum dot structures. Quantum 

control and manipulation of photonic states has also been demonstrated in a variety of systems, typically 

employing the use of high-Q cavities. Physical realizations in this category range from nanophotonic 

cavity quantum electrodynamics systems, to free-space optical cavities, to microwave photons that are 

manipulated in superconducting circuits. Quantum states of vibrational (i.e., phononic) degrees of 

freedom have also been realized; the prime example comes in the form of optomechanical systems, in 

which mechanical motion couples strongly to photons (optical or microwave) in a resonant cavity.

Impact and Outlook

The long-term impact of research in this basic science realm is the realization of novel quantum-coherent 

materials systems and the means to manipulate and probe them for information science. In particular, the 

ability to seamlessly shuttle quantum information between different physical systems will enable 

distributed quantum networks for communication, sensing, and processing. A detailed examination of the 

thermodynamics of quantum machines promises insight into light harvesting for clean energy production 

and bio-inspired detection.
25

PRO 4: Implement New Quantum Methods for Advanced Sensing and Process 

Control

Contributors: Jun Ye, Peter Denes, Stephen Jesse, Mark Kasevich, Chris Monroe, Toni Taylor, Birgitta 

Whaley, and Amir Yacoby

Quantum sensing, along with quantum computing and quantum communication, forms the core of QIP.

Groundbreaking advances in the ability to control QS have brought dramatic improvements in 

measurement science. In general, large ensembles are favored to enhance measurement sensitivity. In 

particular, collections of noninteracting particles such as atoms, molecules, and electronic or nuclear spins 

can be used to maximize precision or sensitivity. Although increasing the number of particles always 

improves the signal-to-noise ratio, inter-particle interactions may limit the measurement performance. 

The outstanding goals in the field of quantum control are thus the synthesis of large QS that can be 

manipulated down to the level of individual, constituent particles and the understanding of the collective 

properties of such systems. Achieving these goals would provide a powerful platform through which 

many-body interactions could be probed and then controlled. However, the long-standing challenge has 

been the extreme difficulty of achieving high-fidelity control of a many-particle system, and it often leads 

to a compromise between the system size and control capabilities. The ability to accurately quantum 

engineer—a key ingredient to realizing meaningful simulations and computations—has been restricted to 

limited system sizes. Recently, a number of technological platforms have emerged that can provide 

answers to the challenge of microscopic manipulation of many-body states of atomic or molecular 

systems.

96 These technologies emerge from microscopic control along several orthogonal axes—space, 

time, number, and energy—to provide new opportunities in the field of quantum many-body physics. 

These advances in the ability to synthesize, manipulate, and detect quantum many-body systems bring 

quantum control into a new exploratory paradigm. In parallel, these novel experimental capabilities 

stimulate new theoretical methods to benchmark and understand observations, and they guide future 

directions that leverage these advances. Interestingly, recent advances also suggest that by using certain 

states of driven quantum matter, one can turn strong interactions from a challenge into an advantage 

resulting in significant enhancements in terms of both sensitivity and bandwidth.

This PRO seeks to advance a long-term scientific goal: to achieve extreme sensing, detection, and control 

capabilities for time/space and fields using emerging quantum technologies; and to develop and apply 

these capabilities to probe material properties and chemical reaction processes. Achieving this goal 

requires developing QS that will nurture emerging quantum technologies, with capabilities including (1) 

producing useful correlations and achieving maximal quantum coherence and robust entanglement; 

(2) understanding entanglement, including classification, quantification, and separate control of quantum 

subsystems; and (3) demonstrating simultaneous time/frequency domain control.

Anticipating material and instrumentation challenges, we should strategize in the following areas:

• Combining single-particle coherence, multiple qubit correlations, and many-particle entanglement to 

maximize measurement gains

• Developing optimal measurement protocols that demonstrate the true advantage of quantum 

approaches and enable new breakthroughs in measurement capabilities

• Connecting quantum entanglement with specific measurement needs and goals and providing 

experimental verification and validation of entanglement-based measurement

As researchers apply these advanced quantum measurement capabilities to materials and chemistry, they 

must understand the complexity of molecules and materials if the quantum advantage is to be gainfully 
26

employed. For example, to implement high-efficiency quantum control of chemical reactions, we need to 

develop novel spectroscopy probes, such as frequency combs, that provide frequency and time domain 

information for exploration and control. We must develop tailored optical pulses for steering chemical 

processes, creating out-of-equilibrium states of molecules for specific reaction gains. We may use 

entangled light with time-frequency correlation to record excited state dynamics in complex systems with 

better spectral resolution. Finally, we are on the verge of developing a new type of imaging instrument 

that utilizes Bell-type readout of entangled electron (or photon) pairs after interacting with materials, thus 

achieving high detection sensitivity while preserving the material properties without strong perturbation 

or damage.

Specific Challenges and Proposed Approaches

The following pages discuss four research areas:

1. Quantum state preparation, measurement, and real-time control of molecular interactions and 

chemical reactions

2. New approaches for microscopy

3. Extreme sensing based on an emerging measurement strategy with long coherence, multiple qubit 

correlations, and many-particle entanglement

4. Understanding the connection of entanglement, thermal dynamics, many-body localization/diffusion

Research along these directions is expected to yield strong impact upon physical science. The aim is to 

achieve sensing capabilities orders of magnitude beyond current standards. These capabilities will enable 

researchers to probe fundamental physics such as quantum–gravity connection and fundamental 

symmetry, as well as facilitate the exploration and understanding of emerging phenomena in strongly 

interacting quantum many-body systems.

1. Quantum state preparation, measurement, and real-time control of molecular 

interactions and chemical reactions

Characterization and control of molecular transformations and chemical reactions are a central topic in 

chemical science, particularly in the areas of catalysis, combustion, and reaction kinetics. The relatively 

young field of quantum control for QIS—which impacts the realization of high-fidelity quantum gates, 

quantum simulation, and advanced metrological methods—has close intellectual and technological 

connections to coherent control of chemical processes ranging from dynamics of coupled spins in electron 

spin resonance and nuclear magnetic resonance studies of molecules, to control of branching pathways in 

chemical reactions. Chemical reaction dynamics was revolutionized in the 1980s by the development of 

molecular beam techniques that enabled the characterization and study of state-to-state molecular 

transformations, both inelastic and reactive.

97 More recently, the rapid development of the field of cold 

molecules has provided unprecedented capabilities in molecular state control for both the internal and 

external degrees of freedom, opening the door to studying and controlling chemical reactions in the fully 

quantum mechanical regime.

98 Also, coherent control techniques have been integrated into ultrafast 

spectroscopic studies of chemical and biological transformations, opening new paths to understanding the 

microscopic dynamics of complex molecular processes.

99 For example, optimal state preparations for 

photosynthetic energy and charge transfer in biosystems have been studied by 2D spectroscopy with 

pulsed laser light. Such experiments involve coherently shaping three phase-locked pulses. Analysis of 

energy flow along different molecular pathways is enhanced by controlled phase shifting of subpulses in 

structured pulse sequences. Recent advances in spectroscopic methods, such as the use of time-resolved 

direct frequency comb spectroscopy, allow mapping of real time kinetics and dynamics on molecular 

potential energy surfaces by simultaneous measurement of reactants, intermediates and products

(Figure 12).

100 A new, exciting scientific field involves the exploration of coherent control methods that 
27

will couple to time-resolved spectroscopies to leverage these new capabilities for probing real-time 

chemical dynamics. The high level of quantum control needed for QIP has led to the development of both 

open loop control paradigms and closed (“feedback”) paradigms. In QIS, coherent control is an enabler of 

high-fidelity operations. Research that builds on or combines these QIS coherent control techniques with

emerging state preparation of molecules and ultrafast spectroscopic techniques will enable transformative 

chemical research targeting metastable molecular species at or near transition states, molecular 

conformational changes relevant to the functional control of biological processes, and the characterization 

of the temporal and energy scales of chemical reactions relevant to combustion and catalysis.

Figure 12. (Left) Potential energy surface of the OH + CO reaction showing the elusive reaction transients

(see TS1 through TS5). | Reproduced from T. Q. Bui et al., Direct measurements of DOCO isomers in the kinetics of OD + 

CO, Science Advances 4, eaao4777, Fig. 1 (2018); copyright Bui et al., some rights reserved; exclusive licensee American 

Association for the Advancement of Science. Distributed under a Creative Commons Attribution Noncommercial 

License 4.0 (Right) An infrared frequency comb watching a reaction in real time, monitoring the transient 

populations of trans-HOCO and cis-HOCO produced in the ambient reaction. | Image courtesy of The Ye 

Group and Steve Burrows, JILA, University of Colorado

2. New approaches for microscopy

Scanning probe microscopes functionalized with individual quantum emitters like color centers and 

quantum dots are an ideal platform for probing material properties at the nanoscale. Because the optical 

properties of any two-level quantum system can be modified by interactions with the vacuum field, 

characterizing the optical response of quantum-emitter functionalized probes through fluorescence 

lifetime imaging microscopy enables the complete nanoscale description of the local density of states. In 

addition, quantum-emitter functionalized probes probe other fields and material properties with state-ofthe art sensitivity. For instance, NV color centers in diamond nanoparticles101 provide a particularly 

promising platform for high-sensitivity detection of electric and magnetic fields at the nanoscale because 

of the long NV spin coherence time and efficient optical spin preparation and characterization techniques. 

The ability to map electrical and magnetic properties of materials at nanometer length scales in ambient 

conditions, and with field sensitivity two orders of magnitude better than that of other scanning probe 

techniques, will enable fundamental advances in the understanding of the evolution of emergent 

properties in quantum materials. Quantum sensors have also begun to exploit noise reductions beyond the 

capabilities of classical devices. For example, micro-electromechanical systems such as those used in 

atomic force microscopes have reduced the noise levels to below the shot noise. The use of squeezed light

with a specific quadrature noise below the standard quantum limit in microscopy and spectroscopy is 

under active investigation. With entangled optical fields, the quantum correlations can be exploited in 

performing differential measurements. To date, low collection efficiency has limited the benefits of 

squeezed light. Enhanced collection efficiency in near-field scanning microscopes, for instance, stands to 

enable the measurement of these enhanced statistics from squeezed excitation fields. 

Electron microscopy allows the visualization of nanometer and subnanometer structures and has played a 

foundational role in advancing science and technology. Recently developed QIS-inspired measurement 
28

strategies appear to enable a new generation of low-damage, possibly noninvasive, electron 

microscopes.

102 The ultimate goal is dynamic imaging of damage-sensitive targets such as polymers and 

proteins, which is currently impossible with existing technology. The basic measurement principle is 

based on the interaction-free measurement (IFM) paradigm, which exploits counterfactual quantum 

measurements—i.e., values that are not directly determined—to realize a class of measurements that are 

damage-free for absorbing targets. In the form originally proposed by Elitzur and Vaidman,

103 the 

protocol is inefficient, since only a fraction of observations result in a damage-free outcome. The 

combination of counterfactual measurement with repeated coherent interrogation enables protocols that 

are near unity efficiency: the presence of an absorber can be inferred with, in principle, a vanishingly 

small probability of an absorbing event. This principle forms the foundation for nondestructive electron 

microscopy.

The quantum imaging protocols converge around common instrument architectures that achieve highefficiency IFM through repeated interrogation of weakly phase shifting (<< 1 rad per pass), weakly 

absorptive (<1% per pass) imaging targets. The simplest implementation is a straightforward multi-pass 

protocol. The general idea is that, although the read-out/detection noise does not depend on the number of 

passes through the sample, the phase shift grows linearly with the number of passes. Thus, the detection 

signal-to-noise ratio improves with the number of passes through the sample in a phase contrast mode.

The phase shift is observed using, for example, phase contrast or dark-field microscopy methods. A 

simple analysis shows that an efficient IFM regime can be realized with this protocol. The efficacy of this 

approach has recently been demonstrated in an optical microscope configuration, where noise below the 

single-pass photon-shot noise limit has been observed with a post-selected, pulsed interrogation 

configuration.

104 Previous analysis has indicated that multi-pass methods are equally effective as methods 

based on exotic entangled probe states and are quantum mechanically optimal for imaging applications.

The potential gains associated with the use of this protocol in electron microscopy have recently been 

analyzed, and it has been shown to enable imaging of small proteins that cannot be imaged using 

conventional transmission electron microscopy methods because of beam damage.

Further improvements are expected from exploiting more complex configurations involving coupled 

modes. The realization of such configurations requires high-efficiency coherent electron diffraction and 

can be implemented with the addition of diffractive elements into a multi-pass microscope. Compact 

electron sources with high coherence and controlled spin states are enabled by plasmonic nanostructures, 

which enhance the optical driving fields in femtosecond pulsed sources. Recent demonstrations show that 

electron beam statistics can reach the shot noise limit. As in optical quantum sensors, the signal-to-noise 

ratio in such systems can be enhanced further by employing squeezed states. Such squeezed states in the 

electron beam would consist of reduced noise in the electron arrival time on detectors and reduced noise 

in a beam’s amplitude or in its phase. Noise reduction in any of these variables would enable enhancedresolution imaging with lower integration times, thereby limiting damage to the sample. The scientific 

payoff for low-damage or near damage-free imaging at the nanometer scale is difficult to overstate. It will 

enable new paths to understanding and engineering of matter and structures at the nanometer scale.

3. Extreme sensing based on an emerging measurement strategy with long 

coherence, multiple qubit correlations, and many-particle entanglement

Quantum-based measurements of many quantities are approaching the standard quantum limit (SQL)—a 

hard limit that prevents further measurement improvements using existing metrology, which relies on the 

quantum properties of ensembles of independent particles. The intellectual development of QIS provides 

an excellent opportunity to break this limit. Quantum interactions and measurement will be employed to 

engineer robust quantum many-body states and to create quantum correlations (entanglement) to both 

improve and surpass the SQL, laying the foundation for new-generation quantum sensors of acceleration, 
29

rotation, electromagnetic field, gravity, and time. These emerging tools will have transformational 

applications ranging from precision sensing and navigation, to quantum communication and QIS.

Control over both the internal and external quantum states of single atoms has led to today’s best 

metrological tools for time/frequency (Figure 13), length, and magnetic fields, and to advanced

capabilities for measuring electric fields, accelerations, rotations, gravity, and temperature.

105 The 

technology is approaching the point at which improvements in sensing capabilities based on individualparticle control have diminishing returns because of physical and practical constraints. The steady 

improvement in measurement precision, accuracy, and bandwidth may thus come to a halt. This situation

presents a clear need for quantum sensors that operate beyond individual-particle measurement 

protocols.

106,107 Many-body interactions can create an energy penalty that protects quantum states against

external perturbations, providing intrinsic immunity to noise.

108 Furthermore, quantum measurement 

noise, present with N independent atoms, provides precision and bandwidth that, as classical noise, 

improve as √N (the SQL); whereas entangled atoms in a sensor can conspire to cancel each other’s 

quantum noise in such a way that improvements can scale as N. For typical N = 103 to 106 particles, this 

affords the opportunity for orders-of-magnitude improvements in sensor precision, bandwidth, and size.

Figure 13. (Left) Optical atomic clock based on a Fermi degenerate quantum gas loaded in a 3D

optical lattice. | Image courtesy of the Ye Group and Steve Burrows, JILA, University of Colorado. (Right) 

Imaging spectroscopy provides clock measurement precision at the 19th decimal point. Reprinted 

figure with permission from G. E. Marti et al., Imaging optical frequencies with 100 mHz precision and 1 mm 

resolution, Phys. Rev. Lett. 120, 103201, 2018. Copyright 2018 by the American Physical Society

Current sensing limits could be surpassed by making the leap to a new generation of quantum sensors that 

exploit an untapped resource for metrology: creating, controlling, and harnessing interactions to create 

robust (noise-resistant) many-body quantum states and entanglement between many atoms. New 

measurement technologies will be developed that rely on interacting many-particle states and on 

entanglement. Of course, this new research direction is challenging: precise control of quantum manybody states requires insights and emerging technologies, and entangled states are intrinsically fragile and 

difficult to create and maintain. So far, entanglement-assisted measurements have been limited to proofof-principle experiments. To connect many-body states to robust sensing applications requires

fundamental new insights and advanced technical competence to dramatically enhance measurement 

capabilities in prototype and world-leading sensors. To mitigate the fragility of entanglement, multiple 

approaches must be developed across several different physical systems for quick, robust creation of 

entanglement and its preservation, via interaction-energy penalties, in the presence of noise. 
30

The rewards are great. A significant improvement in fundamental sensor efficiencies could allow 

technologies with reduced size, higher measurement bandwidth, greater precision, or enhanced accuracy 

to meet the needs of the end user. An important outcome of this research thrust will be the development of 

core insights and fundamental understanding to broadly guide future applications of quantum coherence,

interactions, and entanglement as new and powerful tools for quantum metrology.

4. Understanding the connection of entanglement and quantum many-body dynamics

Quantum correlations are often nonintuitive. Entanglement violates either an intuitive understanding of an 

underlying reality to quantum states, or our notions of measurements being made in local environments.

This non-local quantum correlation was referred to by Schrödinger as “the characteristic trait of quantum 

mechanics, the one that enforces its entire departure from classical lines of thought.”

109 Understanding of 

such quantum correlations has come a long way since Schrödinger’s day. Currently, entanglement is used 

in the context of correlations and in the context of quantum information, where it has a key role in 

providing a valuable resource for tasks in information processing. Thus, entanglement provides insights 

for strongly correlated quantum materials, for understanding the complexity of many-body states, for 

understanding how quantum phase transitions occur, and for when and how self-thermalization occurs in 

closed QS. For QIS, entanglement provides a quantum communication resource for teleportation and 

quantum key distribution, enables quantum algorithms, and is a key component of measurement-based 

quantum computation. As stated in the prior section on “Extreme Sensing,” entanglement will feature 

prominently in quantum metrology. 

The quantum information perspective has shown itself to be particularly useful for understanding 

common features uniting very diverse dynamical phenomena, including quantum chaos, black holes, and 

spin systems in condensed matter. The scrambling of information in these dynamical phenomena can be 

measured by out-of-time–ordered correlators that give insight into the dynamics of thermalization, while 

the rate of growth of entanglement in many-body-localized system reveals information about the nature of 

the localization.

A challenge for the experimental community is to measure these quantum correlations. Although many 

measures of entanglement “witnesses” have been proposed, experimental measurement of these is often 

challenging. Alternatives to direct measurement of entanglement witnesses are indirect methods, such as a 

quantum gas microscope approach, in which some properties of quantum correlations are directly 

characterized experimentally.

110 A good challenge for quantum metrology is to go beyond 

characterization of state properties and ask how much information we have gained, how the information 

gained relates to dynamics or to a given quantum information task, and what correlations motivated by 

quantum information are essential for the existence of the state and its properties that were measured. An 

example of a specific challenge with implications for understanding quantum correlations in a wide 

context is how to distinguish thermal from mixed quantum states.

111 General methods of obtaining state 

information without performing full quantum state tomography, with its high dependence on system size, 

is a task for which quantum information can have critical input. 

A striking development over the past five years is the emergence of protocols for the detection of 

entanglement in large, many-body systems that do not require full quantum state tomography. In parallel, 

the concept of entanglement itself has become a focus of many-body physics, as it has become 

increasingly evident that its properties can finely distinguish varied states of matter. Indeed, entanglement 

plays a key role in subjects ranging from statistical mechanics to topology. Therefore, the development of 

tools to quantify entanglement is central to the goal of characterizing and elucidating quantum many-body 

systems. These protocols for measuring entanglement rely heavily on the preparation of pure quantum 

states—those which are not entangled with other degrees of freedom, i.e., not coupled to a bath—and 

microscopic probes of particle number, position, and energy scales. These capabilities are not available in 
31

traditional condensed matter settings. Hence, ultracold atoms and molecules are a primary avenue to

experimentally characterize and test the role of entanglement in many-body systems, and the continued 

development of a microscopic tool set is vital. For example, through quantum gas microscopy, it has 

become possible to extract all orders of correlation functions for a quantum many-body system. Such 

platforms have also allowed the microscopic tuning of Hamiltonian parameters down to lattice length

scales, allowing for the tailored evolution of a quantum system. Going forward, this approach is ideally 

suited to tackle a variety of new challenges on the horizon, such as testing the emergence of high-Tc

superconductivity in the Fermi-Hubbard model, synthesizing correlated states of topological matter, and 

isolating low-entropy samples of interacting spin systems of polar molecules.

33

3. References

1. US Department of Energy. Quantum Materials for Energy Relevant Technology, Department of 

Energy, Office of Basic Energy Sciences, 2016. Available at http://science.energy.gov/bes/ 

community-resources/reports/.

2. J. M. Rondinelli, and S. J. May. “Oxide interfaces: Instrumental insights,” Nat. Mater. 11, 833 

(2012).

3. E. J. Monkman, C. Adamo, J. A. Mundy, D. E. Shai, J. W. Harter, D. Shen, B. Burganov, D.A.

Muller, D. G. Schlom, and K. M. Shen. “Quantum many-body interactions in digital oxide 

superlattices,” Nat. Mater. 11, 855 (2012).

4. B. Bein, H.-C. Hsing, S. J. Callori, J. Sinsheimer, P. V. Chinta, R. L. Headrick, and M. Dawber. “In 

situ x-ray diffraction and the evolution of polarization during the growth of ferroelectric 

superlattices,” Nat. Commun. 6, 10136 (2015).

5. A. K. Geim and I. V. Grigorieva. “Van der Waals heterostructures,” Nature 499, 419 (2013).

6. T. W. Larsen, K. D. Petersson, F. Kuemmeth, T. S. Jespersen, P. Krogstrup, J. Nygård, and C. M. 

Marcus. “Semiconductor-nanowire-based superconducting qubit,” Phys. Rev. Lett. 115, 127001 

(2015).

7. G. Grosso, H. Moon, B. Lienhard, S. Ali, D. K. Efetov, M. M. Furchi, P. Jarillo-Harrero, M. J.Ford, 

I. Aharonovich, and D. Englund. “Tunable and high-impurity room temperature single-photon 

emission from atomic defects in hexagonal boron nitride,” Nat. Commun. 8, 705 (2017).

8. M. A. Subramanian, C. C. Torardi, J. C. Calabrese, J. Gopalakrishnan, K. J. Morrissey, T. R.Askew, 

R. B. Flippen, U. Chowdhry, and A. W. Sleight. “A new high-temperature superconductor: Bi2Sr3-

xCaxCu2O8+y,” Science 239, 1015 (1988).

9. A. Banerjee1, C. A. Bridges, J.-Q. Yan, A. A. Aczel1, L. Li, M. B. Stone, G. E. Granroth, M. D. 

Lumsden, Y. Yiu, J. Knolle, S. Bhattacharjee, et al.. “Proximate Kitaev quantum spin liquid 

behaviour in a honeycomb magnet,” Nat. Mater. 15, 733 (2016).

10. H. Zhang, C.-X. Liu, X.-L. Qi, X. Dai, Z. Fang, and S.-C. Zhang. “Topological insulators in Bi2Se3, 

Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface,” Nat. Phys. 5, 438 (2009).

11. A. Devarakonda and J. G. Checkelsky. “Topological materials: Monolayers have the edge,” Nat. 

Phys. 13, 63 (2017).

12. B. Huang, G. Clark, E. Navarro-Moratalla, D. R. Klein, R. Cheng, K. L. Seyler, D. Zhong, E. 

Schmidgall, M. A. McGuire, D. H. Cobden, W. Yao, et al. “Layer-dependent ferromagnetism in a 

van der Waals crystal down to the monolayer limit,” Nature 546, 270 (2017).

13. J.-U. Lee, S. Lee, J. H. Ryoo, S. Kang, T. Y. Kim, P. Kim, C.-H. Park, J.-G. Park, and H. Cheong. 

“Ising-type magnetic ordering in atomically thin FePS3,” Nano Lett. 16, 7433 (2016).

14. M. J. Graham, J. M. Zadrozny, M. S. Fataftah, and D. E. Freedman. “Forging solid-state qubit design 

principles in a molecular furnace,” Chem. Mater. 29, 1885 (2017).

15. V. Stavila, A. A. Talin, and M. D. Allendorf. “MOF-based electronic and opto-electronic devices,” 

Chem. Soc. Rev. 43, 5994 (2014).

16. M. D. Allendorf, A. Schwartzberg, V. Stavila, and A. A. Talin. “A roadmap to implementing metalorganic frameworks in electronic devices: Challenges and critical directions,” Chem. Eur. J. 17, 

11372 (2011).
34

17. J. M. Zadrozny, J. Niklas, O. G. Poluektov, D. E. Freedman. “Millisecond coherence time in a 

tunable molecular electronic spin qubit,” ACS Cent. Sci. 1, 488 (2015).

18. G. Aromí, D. Aguilà, P. Gamez, F. Luis, and O. Roubeau. “Design of magnetic coordination 

complexes for quantum computing,” Chem. Soc. Rev. 41, 537 (2012).

19. J. M. Gambetta, J. M. Chow, and M. Steffen. “Autonomous calibration of single spin qubit 

operations,” npj QI 3, 48 (2017).

20. E. Moreno-Pineda, C. Godfrin, F. Balestro, W. Wernsdorfer, and M. Ruben. “Molecular spin qubits 

for quantum algorithms,” Chem. Soc. Rev., Advance Article (2018).

21. J. Ferrando-Soria, E. M. Pineda, A. Chiesa, A. Fernandez, S. A. Magee, S. Carretta, P. Santini, I. J. 

Vitorica-Yrezabal, F. Tuna, G. A. Timco, E. J. L. McInnes, and R. E. P. Winpenny. “A modular 

design of molecular qubits to implement universal quantum gates,” Nat. Commun. 7, 11377s (2016).

22. G. A. Timco, S. Carretta, F. Troiani, F. Tuna, R. J. Pritchard, C. A. Muryn, E. J. L. McInnes, A. 

Ghirri, A. Candini, P. Santini, G. Amoretti, et al. “Engineering the coupling between molecular spin 

qubits by coordination chemistry,” Nature Nanotechnol. 4, 173 (2009).

23. M. J. Graham, C. Yu, M. Krzyaniak, M. R. Wasielewski, and D. E. Freedman. “Synthetic approach 

to determine the effect of nuclear spin distance on electronic spin decoherence,” J. Am. Chem. Soc. 

139, 3196 (2017).

24. C. Yu, M. J. Graham, J. M. Zadrozny, J. Niklas, M. Krzyaniak, M. R. Wasielewski, O. G. Poluektov, 

and D. E. Freedman. “Long coherence times in nuclear spin-free vanadyl qubits,” J. Am. Chem. Soc. 

138, 14678 (2016).

25. P. Falcaro, R. Ricco, C. M. Doherty, K. Liang, A. J. Hill, and M. J. Styles. “MOF positioning 

technology and device fabrication,” Chem. Soc. Rev. 43, 5513 (2014).

26. A. Y. Kitaev. “Fault-tolerant quantum computation by anyons,” Ann. Phys. (N Y) 303, 2 (2003).

27. G.P. Collins. “Computing with quantum knots,” Sci. Am. 294, 56 (2006).

28. R. Balian and N. R. Werthamer. “Superconductivity with pairs in a relative p Wave,” Phys. Rev. 131, 

1553 (1963).

29. B. van Heck, A. R. Akhmerov, F. Hassler, M. Burrello, and C.W.J. Beenakker. “Coulomb-assisted 

braiding of Majorana fermions in a Josephson junction array,” New J. Phys. 14, 035019 (2012).

30. T. Hyart, B. van Heck, I. C. Fulga, M. Burrello, A. R. Akhmerov, and C.W.J. Beenakker. “Fluxcontrolled quantum computation with Majorana fermions,” Phys. Rev. B 88, 035121 (2013).

31. A. P. MacKenzie and Y. Maeno. “The superconductivity of Sr2RuO4 and the physics of spin-triplet 

pairing,” Rev. Mod. Phys. 75, 657 (2003).

32. C. Kallin. “Chiral p-wave order in Sr2RuO4,” Rep. Prog. Phys. 75, 042501 (2012).

33. Y. Krockenberger, M. Uchida, K. S. Takahashi, M. Nakamura, M. Kawasaki, and Y. Tokura. 

“Growth of superconducting Sr2RuO4 thin films,” Appl. Phys. Lett. 97, 082502 (2010).

34. J. Cao, D. Massarotti, M. E. Vickers, A. Kursumovic, A. Di Bernardo, J.W.A. Robinson, F. Tafuri, 

L. MacManus-Driscoll, and M. G. Blamire. “Enhanced localized superconductivity inSr2RuO4 thin 

film by pulsed laser deposition,” Supercondu. Sci. Technol. 29, 095005 (2016).

35. C. W. Hicks, D. O. Brodsky, E. A. Yelland, A. S. Gibbs, J.A.N. Bruin, M. E. Barber, S. D. Edkins, 

Nishimura, S. Yonezawa, Y. Maeno, and A. P. Mackenzie. “Strong increase of Tcof Sr2RuO4 under 

both tensile and compressive strain,” Science 344, 283 (2014).
35

36. A. Steppke, L. Zhao, M. E. Barber, T. Scaffidi, F. Jerzembeck, H. Rosner, A. S. Gibbs, Y. Maeno, S. 

H. Simon, A. P. Mackenzie, and C. W. Hicks. “Strong peak in Tc of Sr2RuO4 under uniaxial 

pressure,” Science 355, eaaf9398 (2017).

37. Y-T. Hsu, W. Cho, A. F. Rebola, B. Burganov, C. Adamo, K. M. Shen, D. G. Schlom, C. J. Fennie, 

and E.-A. Kim. “Manipulating superconductivity in ruthenates through Fermi surface engineering,” 

Phys. Rev. B 94, 045118 (2016).

38. Y.-T. Hsu, A. Vaezi, M. H. Fischer, and E.-A. Kim. “Topological superconductivity in monolayer 

transition metal dichalcogenides,” Nat. Commun. 8, 14985 (2017).

39. J-H. She, C. H. Kim, C. J. Fennie, M. J. Lawler, and E-A. Kim. “Topological superconductivity in 

metal/quantum-spin-ice heterostructures,” arXiv:1603.02692 (in press at npj Quantum Materials 

(2017).

40. L. Fu and C. L. Kane. “Superconducting proximity effect and Majorana fermions at the surface of a 

topological insulator,” Phys. Rev. Lett. 100, 096407 (2008).

41. J. D. Sau, R. M. Lutchyn, S. Tewari, and S. Das Sarma. “Generic new platform for topological 

quantum computation using semiconductor heterostructures,” Phys. Rev. Lett. 104, 040502 (2010).

42. V. Mourik, K. Zuo, S. M. Frolov, S. R. Plissard, E.P.A.M. Bakkers, and L. P. Kouwenhoven. 

“Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices,” 

Science 336, 1003 (2012).

43. S. Gazibegovic, D. Car, H. Zhang, S. C. Balk, J. A. Logan, M.W.A. de Moor, M. C. Cassidy, R. 

Schmits, D. Xu, G. Wang, P. Krogstrup, et al. “Epitaxy of advanced nanowire quantum devices,” 

Nature 548, 434 (2017).

44. H. Zhang, C.-X. Liu, S. Gazibegovic, D. Xu, J. A. Logan, G. Wang, N. van Loo, J.D.S. Bommer, 

M.W.A. de Moor, D. Car, R.L.M. Op het Veld, et al. “Quantized Majorana conductance,” 

ArXiv:1710.10701 (2017).

45. S. Hart, H. Ren, M. Kosowsky, G. Ben-Shach, P. Leubner, C. Brüne, H. Buhmann, L. W. 

Molenkamp, B. I. Halperin and A. Yacoby. “Controlled finite momentum pairing and spatially 

varying order parameter in proximitized HgTe quantum wells,” Nat. Phys. 13, 87 (2017).

46. F. Pientka, A. Keselman, E. Berg, A. Yacoby, A. Stern, and B. I. Halperin. “Topological 

superconductivity in a planar Josephson junction,” Phys. Rev. X 7, 021032 (2017).

47. O. Custance, R. Perez, and S. Morita. “Atomic force microscopy as a tool for atom manipulation,” 

Nat. Nanotechnol. 4, 803 (2009).

48. P. Ball. “Elusive triangulene created by moving atoms one at a time,” Nature 542, 284 (2017).

49. D. G. de Oteyza, P. Gorman, Y-C. Chen, S. Wickenburg, A. Riss, D. J. Mowbray, G. Etkin, Z. 

Pedramrazi, H-Z. Tsai, A. Rubio, M. F. Crommie, and F. R. Fischer. “Direct imaging of covalent 

bond structure in single-molecule chemical reactions,” Science 340, 1434 (2013).

50. L. Tapasztó, G. Dobrik, P. Lambin, and L. P. Biró. “Tailoring the atomic structure of graphene 

nanoribbons by scanning tunneling microscope lithography,” Nat. Nanotechnol. 3, 397 (2008).

51. S. V. Kalinin, A. Borisevich, and S. Jesse. “Fire up the atom forge,” Nature 539, 485 (2016)

52. J. R. Weber, W. F. Koehl, J. B. Varley, A. Janotti, B. B. Buckley, C. G. Van de Walle, and D. D. 

Awschalom. “Quantum computing with defects,” Proc. Natl. Acad. Sci. 107, 8513 (2010).

53. A. L. Falk, B. B. Buckley, G. Calusine, W. F. Koehl, V. V. Dobrovitski, A. Politi, C. A. Zorman, P. 

X.-L. Feng, and.D. D. Awschalom. “Polytype control of spin qubits in silicon carbide,” Nat. 

Commun. 4, 1819 (2013).
36

54. M. Y. Simmons. “Quantum computing in silicon,” IEEE Conference: IEEE International Electron 

Devices Meeting (IEDM), Washington, DC, December 7–9, 2015.

55. D. A. Muller. “Structure and bonding at the atomic scale by scanning transmission electron 

microscopy,” Nat. Mater. 8, 263 (2009).

56. F. Börrnert, L. Fu, S. Gorantla, M. Knupfer, B. Büchner, and M. H. Rümmeli. “Programmable subnanometer sculpting of graphene with electron beams,” ACS Nano 6, 10327 (2012).

57. M. K. Santala, B. W. Reed, T. Topuria, S. Raoux, S. Meister, Y. Cui, T. LaGrange, G. H. Campbell, 

and N. D. Browning. “Nanosecond in situ transmission electron microscope studies of the reversible 

Ge2Sb2Te5 crystalline ↔ amorphous phase transformation,” J. Appl. Phys. 111, 024309 (2012).

58. J. A. Rodriguez-Manzo and F. Banhart. “Creation of individual vacancies in carbon nanotubes by 

using an electron beam of 1 Å diameter,” Nano Lett. 9, 2285 (2009).

59. O. Dyck, S. Kim, S. V. Kalinin, and S. Jesse. “Single atom manipulation and control in a scanning

transmission electron microscope,” arXiv:1708.01523 (2017).

60. O. Dyck, S. Kim, E. Jimenez-Izal, A. N. Alexandrova, S. V. Kalinin, and S. Jesse. “Assembling diand multiatomic Si clusters in graphene via electron beam manipulation,” arXiv:1710.09416 (2017).

61. A. Losquin and M. Kociak. “Link between cathodoluminescence and electron energy loss 

spectroscopy and the radiative and full electromagnetic local density of states,” ACS Photonics 2, 

1619 (2015).

62. Manipulating Quantum Coherence in Solid State Systems, eds. M. E. Flatté and I. Tifrea, Springer, 

Heidelberg, 2007.

63. Semiconductor Spintronics and Quantum Computation, eds. D. D. Awschalom, N. Samarth, and D. 

Loss, Springer, Heidelberg, 2002.

64. D. D. Awschalom and M. E. Flatté. “Challenges for semiconductor spintronics,” Nat. Phys. 3, 153 

(2007).

65. Z.-L. Xiang, S. Ashhab, J. Q. You, and F. Nori. “Hybrid quantum circuits: Superconducting circuits 

interacting with other quantum systems,” Rev. Mod. Phys. 85, 623 (2013).

66. M. H. Devoret and R. J. Schoelkopf. “Superconducting circuits for quantum information: An 

outlook,” Science 339, 1169 (2013).

67. D. D. Awschalom, L. C. Bassett, A. S. Dzurak, E. L. Hu, and J. R. Petta. “Quantum spintronics: 

Engineering and manipulating atom-like spins in semiconductors,” Science 339, 1174 (2013).

68. G. Balasubramanian, P. Neumann, D. Twitchen, M. Markham, R. Kolesov, N. Mizuochi, J. Isoya, 

J. Achard, J. Beck, J. Tissler, V. Jacques, et al. “Ultralong spin coherence time in isotopically 

engineered diamond,” Nat. Mater. 8, 383 (2009).

69. A. M. Tyryshkin, S. Tojo, J. J. L. Morton, H. Riemann, N. V. Abrosimov, P. Becker, H.-J. Pohl, T. 

Schenkel, M. L. W. Thewalt, K. M. Itoh, and S. A. Lyon. “Electron spin coherence exceeding 

seconds in high-purity silicon,” Nat. Mater. 11, 143 (2012).

70. M. Reagor, W. Pfaff, C. Axline, R. W. Heeres, N. Ofek, K. Sliwa, E. Holland, C. Wang, J. Blumoff, 

K. Chou, M. J. Hatridge, et al. “Quantum memory with millisecond coherence in circuit QED,” 

Phys. Rev. B 94, 014506 (2016).

71. J. Berezovsky, M. H. Mikkelsen, N. G. Stoltz, L. A. Coldren, and D. D. Awschalom. “Picosecond 

coherent optical manipulation of a single electron spin in a quantum dot,” Science 320, 349 (2008).
37

72. J. van Bree and M. E. Flatté. “Atomic-scale magnetometry of dynamic magnetization,” Phys. Rev. 

Lett. 118, 087601 (2017).

73. M. Gaudin. “Diagonalisation d’une classe d’hamiltoniens de spin,” J. Phys. France 37, 1087 (1976).

74. L. T. Hall, J. H. Cole, and L.C.L. Hollenberg. “Analytic solutions to the central-spin problem for 

nitrogen-vacancy centers in diamond,” Phys. Rev. B 90, 075201 (2014).

75. G. D. Fuchs, V. V. Dobrovitski, D. M. Toyli, F. J. Heremans, and D. D. Awschalom. “Gigahertz 

dynamics of a strongly driven single quantum spin,” Science 326, 1520 (2009).

76. M. N. Leuenberger, M. E. Flatté and D. D. Awschalom. “Proposal for measuring the entanglement of 

nearby spins by multiphoton interference,” EPL 71, 387 (2005).

77. I. Aharonovich, A. D. Greentree and S. Prawer. “Diamond photonics,” Nat. Photonics 5, 397 (2011).

78. M. Wallquist, K. Hammerer, P. Rabl, M. Lukin, and P. Zoller. “Hybrid quantum devices and 

quantum engineering,” Phys. Scr. T137, 014001 (2009).

79. N. Gisin and R. Thew. “Quantum communication,” Nat. Photonics 1, 165 (2007).

80. J. Yin, Y. Cao, Y.-H. Li, S.-K. Liao, L. Zhang, J.-G. Ren, W.-Q. Cai, et al. “Satellite-based 

entanglement distribution over 1200 kilometers,” Science 356, 1140 (2017).

81. J. Nunn. “Viewpoint: A solid footing for a quantum repeater,” Physics 10, 55 (2017).

82. M. D. Eisaman, J. Fan, A. Migdall, and S. V. Polyakov. “Single-photon sources and detectors,” 

invited review article, Rev. Sci. Inst. 82, 071101 (2011).

83. A. Ishizaki and G. R. Fleming. “Quantum coherence in photosynthetic light harvesting,” Annu. Rev. 

Condens. Matter Phys. 3, 333 (2012).

84. M. Sarovar, A. Ishizaki, G. R. Fleming and K. B. Whaley. “Quantum entanglement in photosynthetic 

light-harvesting complexes, ” Nat. Phys. 6, 16592 (2010).

85. A. Shnirman, G. Schön, I. Martin, and Y. Makhlin. “1/f noise and two-level systems in Josephson 

qubits, ” in K. Scharnberg and S. Kruchinin, eds., Electron Correlation in New Materials and 

Nanosystems, NATO Science Series, vol 241, Springer, Dordrecht, 343 (2007).

86. J. Eroms, L. C. van Schaarenburg, E. F. C. Driessen, J. H. Plantenberg, C. M. Huizinga, R. N. 

Schouten, A. H. Verbruggen, C. J. P. M. Harmans, and J. E. Mooij. “Low-frequency noise in 

Josephson junctions for superconducting qubits, ” Appl. Phys. Lett. 89, 122516 (2006).

87. P. Kumar, S. Sendelbach, M. A. Beck, J. W. Freeland, Z. Wang, H. Wang, C. C. Yu, R. Q. Wu, D. P. 

Pappas, and R. McDermott. “Origin and reduction of 1/f magnetic flux noise in superconducting 

devices, ” Phys. Rev. Applied 6, 041001 (2016).

88. W. D. Oliver and P. B. Welander. “Materials in superconducting qubits,” MRS Bulletin 18, 816 

(2013).

89. R. W. Andrews, R. W. Peterson, T. P. Purdy, K. Cicak, R. W. Simmonds, C. A. Regal, and K. W. 

Lehnert. “Bidirectional and efficient conversion between microwave and optical light,” Nat. Phys. 

10, 321 (2014).

90. N. V. Vitanov, A. A. Rangelov, B. W. Shore, and K. Bergmann. “Stimulated Raman adiabatic 

passage in physics, chemistry and beyond,” Rev. Mod. Phys. 89, 941 (2017).

91. E. Torrontegui, S. Ibáñez, S. Martínez-Garaot, M. Modugno, A. del Campo, D. Guéry-Odelin, 

A. Ruschhaupt, X. Chen, and J. Muga. “Shortcuts to adiabaticity, ” Adv. At. Mol. Opt. Phy. 62, 

Academic Press, Cambridge, 117 (2013).
38

92. A. Baksic, H. Ribeiro, and A. A. Clerk. “Speeding up adiabatic quantum state transfer by using 

dressed states,” Phys. Rev. Lett. 116, 230503 (2016).

93. J. Pekola. “Towards quantum thermodynamics in electronic circuits,” Nat. Phys. 11, 118 (2015); P. 

Kammerlander and J. Anders. “Coherence and measurement in quantum thermodynamics,” Sci Rep. 

6, 22174 (2016); M. Scully, K. R. Chapin, K. E. Dorfman, M. B Kim, and A. Svidvinsky. “Quantum 

heat engine power can be increased by noise-induced coherence,” Proc. Nat. Acad. Sci. USA 108, 

15097 (2011); M. Lostaglio, D. Jennings, and T. Rudolph. “Description of quantum coherence in 

thermodynamic processes requires constraints beyond free energy,” Nat. Comm. 6, 6383 (2015).

94. R. Uzdin, A. Levy, and R. Kosloffm. “Equivalence of quantum heat machines, and quantumthermodynamic signatures,” Phys. Rev. X 5, 031044 (2015).

95. J. Rossnagel, S. T. Dawkins, K. N. Tolazzi, O. Abah, E. Lutz, F. Schmidt-Kaler, and K. Singer. “A 

single-atom heat engine,” Science 352, 325 (2016).

96. W. S. Bakr, J. I. Gillen, A. Peng, S. Folling, and M. Greiner. “A quantum gas microscope for 

detecting single atoms in a Hubbard-regime optical lattice,” Nature 462, 74 (2009).

97. G. Scoles, D. Bassi, and U. Buck, eds. Atomic and Molecular Beam Methods, vol. 1, Oxford 

University Press, 1988, p. 752.

98. J. L. Bohn, A. M. Rey, and J. Ye. “Cold molecules: Progress in quantum engineering of chemistry 

and quantum matter,” Science 357, 1002 (2017).

99. M. Shapiro and P. Brumer. Quantum Control of Molecular Processes, John Wiley and Sons, 2012.

100. B. J. Bjork, T. Q. Bui, O. H. Hecki, P. B. Changala, B. Spaun, P. Heu, D. Follman, C. Deutsch, G. D. 

Cole, M. Aspelmeyer, M. Okumura, and J. Ye. “Direct frequency comb measurement of OD plus 

CO → DOCO kinetics,” Science 354, 444 (2016).

101. G. Kucsko, P. C. Maurer, N. Y. Yao, M. Kubo, J. Noh, P. K. Lo, H. Park, and M. D. Lukin. 

“Nanometre-scale thermometry in a living cell,” Nature 500, 54 (2013).

102. O. L. Krivanek, M. F. Chisholm, V. Nicolosi, T. J. Pennycook, G. J. Corbin, N. Dellby, M. F. 

Murfitt, C. S. Own, Z. S. Szilagyi, M. P. Oxley, S. T. Pantelides, and S. J. Pennycook. “Atom-byatom structural and chemical analysis by annular dark-field electron microscopy,” Nature 464, 571 

(2010).

103. A. C. Elitzur and L. Vaidman. “Quantum-mechanical interaction-free measurements,” Found. Phys. 

23, 987 (1993).

104. T. Juffmann, S. A. Koppell, B. B. Klopfer, C. Ophus, R. M. Glaeser, and M. A. Kasevich. “Multipass transmission electron microscopy,” Sci. Rep. 7 (2017).

105. B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishop, X. Zhang, W. Zhang, S. L. 

Bromley, and J. Ye. “An optical lattice clock with accuracy and stability at the 10(−

18) level,” 

Nature 506, 71 (2014).

106. J. G. Bohnet, K. C. Cox, M. A. Norcia, J. M. Weiner, Z. Chen, and J. K. Thompson. “Reduced spin 

measurement back-action for a phase sensitivity ten times beyond the standard quantum limit,” Nat. 

Photonics 8, 731 (2014).

107. O. Hosten, N. J. Engelsen, R. Krishnakumar, and M. A. Kasevich. “Measurement noise 100 times 

lower than the quantum-projection limit using entangled atoms,” Nature 529, 505 (2016).

108. S. L. Campbell, R. B. Hutson, G. E. Marti, A. Goban, N. D. Oppong, R. L. McNally, L. 

Sonderhouse, J. M. Robinson, W. Zhang, B. J. Bloom, and J. Ye. “A Fermi-degenerate threedimensional optical lattice clock,” Science 358, 90 (2017).
39

109. E. Schrödinger. “Discussion of probability relations between separated systems,” Mathematical 

Proceedings of the Cambridge Philosophical Society, 31(4), 555 (1935). 

doi:10.1017/S0305004100013554]

110. M. F. Parsons, A. Mazurenko, C. S. Chiu, G. Ji, D. Grief, and M. Greiner. “Site-resolved 

measurement of the spin-correlation function in the Fermi-Hubbard model,” Science 353, 1253 

(2016).

111. A. M. Kaufman, M. E. Tai, A. Lukin, M. Rispoli, R. Schittko, P. M. Preiss, and M. Greiner. 

“Quantum thermalization through entanglement in an isolated many-body system,” Science 353, 794 

(2016).

41

Appendix A: Workshop Participants

BES Roundtable on Opportunities for Basic Research for 

Next-Generation Quantum Systems

Chair: David Awschalom, University of Chicago/Argonne National Laboratory

Co-Chair: Hans Christen, Oak Ridge National Laboratory

Panel: Opportunities to Advance Scientific Understanding to Enable QIS

David Awschalom, University of Chicago/Argonne National Laboratory

Michael Flatté, University of Iowa

Danna Freedman, Northwestern University

Giulia Galli, University of Chicago

Chris Monroe, University of Maryland

William Oliver, Massachusetts Institute of Technology

Nitin Samarth, Pennsylvania State University

Birgitta Whaley, University of California–Berkeley

Amir Yacoby, Harvard University

Panel: Opportunities to Advance Instrumentation for and Based on QIS

Hans Christen, Oak Ridge National Laboratory

Peter Denes, Lawrence Berkeley National Laboratory

Stephen Jesse, Oak Ridge National Laboratory

Mark Kasevich, Stanford University

Chris Palmstrom, University of California–Santa Barbara

Darrell Schlom, Cornell University

Irfan Siddiqi, University of California–Berkeley/Lawrence Berkeley National Laboratory

Toni Taylor, Los Alamos National Laboratory

Jun Ye, JILA, University of Colorado

PRO 1: Advance Artificial Quantum Coherent Systems with Unprecedented 

Functionality for QIS

Amir Yacoby, Harvard University: Lead

Peter Denes, Lawrence Berkeley National Laboratory

Stephen Jesse, Oak Ridge National Laboratory

Danna Freedman, Northwestern University

Giulia Galli, University of Chicago

Darrell Schlom, Cornell University

Nitin Samarth, Pennsylvania State University

Chris Palmstrom, University of California–Santa Barbara

PRO 2: Enhance Creation and Control of Coherence in Quantum Systems

Michael Flatté, University of Iowa: Lead

Darrell Schlom, Cornell University

Irfan Siddiqi, University of California–Berkeley/ Lawrence Berkeley National Laboratory

Toni Taylor, Los Alamos National Laboratory
42

PRO 3: Discover Novel Approaches for Quantum-to-Quantum Transduction

Irfan Siddiqi, University of California–Berkeley/ Lawrence Berkeley National Laboratory: Lead

David Awschalom, University of Chicago/Argonne National Laboratory

William Oliver, Massachusetts Institute of Technology

Birgitta Whaley, University of California–Berkeley

PRO 4: Implement New Quantum Methods for Advanced Sensing and Process Control

Jun Ye, JILA, University of Colorado: Lead

Amir Yacoby, Harvard University: Lead

Hans Christen, Oak Ridge National Laboratory

Peter Denes, Lawrence Berkeley National Laboratory

Stephen Jesse, Oak Ridge National Laboratory

Mark Kasevich, Stanford University

Chris Monroe, University of Maryland

Toni Taylor, Los Alamos National Laboratory

Birgitta Whaley, University of California–Berkeley

Invited Participants

David Awschalom, University of Chicago/Argonne National Laboratory

Hans Christen, Oak Ridge National Laboratory

Peter Denes, Lawrence Berkeley National Laboratory

Michael Flatté, University of Iowa

Danna Freedman, Northwestern University

Giulia Galli, University of Chicago

Stephen Jesse, Oak Ridge National Laboratory

Mark Kasevich, Stanford University

Chris Monroe, University of Maryland/IonQ

William Oliver, Massachusetts Institute of Technology

Chris Palmstrøm, University of California–Santa Barbara

Nitin Samarth, Pennsylvania State University

Darrell Schlom, Cornell University

Irfan Siddiqi, University of California–Berkeley/Lawrence Berkeley National Laboratory

Toni Taylor, Los Alamos National Laboratory

Birgitta Whaley, University of California–Berkeley

Amir Yacoby, Harvard University

Jun Ye, JILA, University of Colorado

Invited Observers

Dimitri Argyriou, AMES Laboratory

Kramer Akli, DOE Office of Science, Fusion Energy Sciences

Paul Bayer, DOE Office of Science, Biological and Environmental Research 

Chuck Black, Brookhaven National Laboratory

Jeff Blackburn, National Renewable Energy Laboratory

Steve Binkley, DOE Office of Science

Tof Carim, DOE Office of Science, High Energy Physics

Lali Chatterjee, DOE Office of Science, High Energy Physics

Claire Cramer, DOE Office of Science, Advanced Scientific Computing Research
43

David Dean, Oak Ridge National Laboratory 

Jim Davenport, DOE Office of Science, Basic Energy Sciences 

Tom Devereaux, SLAC National Accelerator Laboratory

Chris Fecko, DOE Office of Science, Basic Energy Sciences

Bruce Garrett, DOE Office of Science, Basic Energy Sciences

Matthias Graf, DOE Office of Science, Basic Energy Sciences

Barbara Helland, DOE Office of Science, Advanced Scientific Computing Research

Linda Horton, DOE Office of Science, Basic Energy Sciences

Jim Horwitz, DOE Office of Science, Basic Energy Sciences

Helen Kerch, DOE Office of Science, Basic Energy Sciences

Refik Kortan, DOE Office of Science, Basic Energy Sciences

Jeff Krause, DOE Office of Science, Basic Energy Sciences

Sriram Krishnamoorthy, Pacific Northwest National Laboratory

Harriet Kung, DOE Office of Science, Basic Energy Sciences

Peter Lee, DOE Office of Science, Basic Energy Sciences

Eliane Lessner, DOE Office of Science, Basic Energy Sciences

Vince Lordi, Lawrence Livermore National Laboratory

John Mandrekas, DOE Office of Science, Fusion Energy Sciences 

George Maracas, DOE Office of Science, Basic Energy Sciences

Gail McLean, DOE Office of Science, Basic Energy Sciences

Raul Miranda, DOE Office of Science, Basic Energy Sciences 

Shashank Misra, Sandia National Laboratories

Joel Moore, Lawrence Berkeley National Laboratory

Jim Murphy, DOE Office of Science, Basic Energy Sciences

Mick Pechan, DOE Office of Science, Basic Energy Sciences

Mark Pederson, DOE Office of Science, Basic Energy Sciences

Jim Rhyne, DOE Office of Science, Basic Energy Sciences

Tom Russell, DOE Office of Science, Basic Energy Sciences

John Sarrao, Los Alamos National Laboratory

Andy Schwartz, DOE Office of Science, Basic Energy Sciences

Tom Settersten, DOE Office of Science, Basic Energy Sciences

Jim Siegrist, DOE Office of Science, High Energy Physics

Ceren Susut-Bennett, DOE Office of Science, Advanced Scientific Computing Research

Thiyaga Thiyagarajan, DOE Office of Science, Basic Energy Sciences

Robert Tschirhart, Fermi National Accelerator Laboratory

Jane Zhu, DOE Office of Science, Basic Energy Sciences

45

Appendix B: Workshop Agenda

BES Roundtable on Opportunities for Basic Research for 

Next-Generation Quantum Systems

Gaithersburg Marriott Washingtonian Center ● October 30–31, 2017

Monday, October 30, 2017

7:30 – 8:30 a.m. Registration and breakfast – Lakeside Room

Opening Session — Lakeside Room

8:30 – 9:00 a.m. Welcome and Roundtable Charge

Steve Binkley, Acting Director, Office of Science

Harriet Kung, Associate Director of Science for Basic Energy Sciences

9:00 – 9:45 a.m. Welcome, Roundtable Structure, and Summary of Homework

David Awschalom, University of Chicago/Argonne National Laboratory (Chair)

Hans Christen, Oak Ridge National Laboratory (Co-Chair)

9:45 – 10:00 a.m. Break

10:00 – 11:00 a.m. Group Discussion

11:00 – Noon Break and Group Discussion (continued)

12:00 – 1:00 p.m. Working lunch – Lakeside Room

1:00 – 4:45 p.m. Parallel Panel Sessions

Opportunities to Advance Scientific Understanding to Enable QIS – Lakeside

David Awschalom

Opportunities to Advance Instrumentation for and Based on QIS – Salon G

Hans Christen

3:00 – 4:00 p.m. Refreshments available – Lakeside

4:45 – 5:30 Draft Group Presentations – Lakeside

5:30 – 7:00 p.m. Break for dinner (location for participants TBA)

7:00 – 10:00 p.m. Parallel Panel Discussions (continued) – Lakeside

Tuesday, October 31, 2017

7:30 – 8:30 a.m. Breakfast – Lakeside

8:00 – 10:00 a.m. Finalization of Group Presentations

Opportunities to Advance Scientific Understanding to Enable QIS – Lakeside

David Awschalom

Opportunities to Advance Instrumentation for and Based on QIS – Salon G

Hans Christen

10:00 – 11:30 a.m. Presentation and Discussion – Lakeside

11:30 – Noon Roundtable adjourned

Disclaimer

This report was prepared as an account of work sponsored by an 

agency of the United States Government. Neither the United 

States Government nor any agency thereof, nor any of their 

employees, makes any warranty, express or implied, or assumes 

any legal liability or responsibility for the accuracy, completeness, 

or usefulness of any information, apparatus, product, or process 

disclosed, or represents that its use would not infringe privately 

owned rights. Reference herein to any specific commercial 

product, process, or service by trade name, trademark, 

manufacturer, or otherwise, does not necessarily constitute or 

imply its endorsement, recommendation, or favoring by the United 

States Government or any agency thereof. The views and opinions 

of authors expressed herein do not necessarily state or reflect 

those of the United States Government or any agency thereof.