Query: Ultrafast optical control of orbital and spin dynamics in a solid-state defect

Candidate papers:

abstract: Manipulating a defect in diamond Like magnetic storage in today's classical computers, tiny "magnets" associated with electronic and nuclear states spins are promising qubits (quantum bits) for the future. Electronic spins in special defects in diamond called nitrogen vacancy (NV) centers are one example. Whereas most applications focus on the least energetic (ground) state of an NV center, Bassett et al. explored the properties of the higher energy (excited) state (see the Perspective by Childress) They used light pulses to bring the system into the excited state and to vary the time it stayed there. In this way, they could both deduce the electronic structure of the excited state and manipulate the ground state spin. Similar methods may be applicable to other quantum information systems. Science, this issue p. 1333; see also p. 1247 The electronic spin in a nitrogen vacancy center in diamond is manipulated with optical pulses alone. [Also see Perspective by Childress] Atom scale defects in semiconductors are promising building blocks for quantum devices, but our understanding of their material dependent electronic structure, optical interactions, and dissipation mechanisms is lacking. Using picosecond resonant pulses of light, we study the coherent orbital and spin dynamics of a single nitrogen vacancy center in diamond over time scales spanning six orders of magnitude. We develop a time domain quantum tomography technique to precisely map the defect's excited state Hamiltonian and exploit the excited state dynamics to control its ground state spin with optical pulses alone. These techniques generalize to other optically addressable nanoscale spin systems and serve as powerful tools to characterize and control spin qubits for future applications in quantum technology.
author_names: Lee C Bassett

F Joseph Heremans

David J Christle

Christopher G Yale

Guido Burkard

Bob B Buckley

David D Awschalom
title: Ultrafast optical control of orbital and spin dynamics in a solid state defect
venue: Science
year: 2014

abstract: Optically addressable spin defects in solid state materials have shown great potential for applications ranging from metrology to quantum information processing. Many of these experiments require a detailed understanding of the full Hamiltonian dynamics in order to develop precise quantum control. Here we use picosecond resonant optical pulses to investigate the coherent orbital and spin dynamics of the nitrogen vacancy (NV) center in diamond, over timescales spanning six orders of magnitude. We implement an ultrafast optical pump probe technique to study the NV center's orbital doublet, spin triplet excited state at cryogenic temperatures (T 20 K) where the excited state becomes stable and optically coherent with the ground state. This technique, coupled with optical polarization selection rules, allows us to probe the coherent orbital dynamics of the NV center's excited state [1] These experiments reveal dynamics on femtosecond to nanosecond timescales due to the interplay between the ground and excited state orbital levels. This all optical technique also provides a method to dynamically control the spin state of the NV center by harnessing the excited state structure. Through studying the spin dynamics of the NV center with coherent pulses of light, we are able to rotate the spin state on sub nanosecond timescales. Furthermore, by tuning the excited state spin Hamiltonian with an external magnetic eld, we demonstrate arbitrary axis spin rotations through controlled unitary evolution of the spin state. Extending this to the full excited state manifold, we develop a time domain quantum tomography technique to precisely map the NV center's excited state Hamiltonian. These techniques generalize to other systems and can be a powerful tool in characterizing and controlling qubits in other optically addressable spin systems.
author_names: F Joseph Heremans
title: Quantum control of orbital and spin dynamics in diamond using ultrafast optical pulses
year: 2015

abstract: Scalable quantum networking requires quantum systems with quantum processing capabilities. Solid state spin systems with reliable spin optical interfaces are a leading hardware in this regard. However, available systems suffer from large electron phonon interaction or fast spin dephasing. Here, we demonstrate that the negatively charged silicon vacancy centre in silicon carbide is immune to both drawbacks. Thanks to its 4A2 symmetry in ground and excited states, optical resonances are stable with near Fourier transform limited linewidths, allowing exploitation of the spin selectivity of the optical transitions. In combination with millisecond long spin coherence times originating from the high purity crystal, we demonstrate high fidelity optical initialization and coherent spin control, which we exploit to show coherent coupling to single nuclear spins with ~1 kHz resolution. The summary of our findings makes this defect a prime candidate for realising memory assisted quantum network applications using semiconductor based spin to photon interfaces and coherently coupled nuclear spins.Point defects in solids have potential applications in quantum technologies, but the mechanisms underlying different defects' performance are not fully established. Nagy et al. show how the wavefunction symmetry of silicon vacancies in SiC leads to promising optical and spin coherence properties.
author_names: Roland Nagy

Matthias Niethammer

Matthias Widmann

Yu-Chen Chen

Peter Udvarhelyi

Cristian Bonato

Jawad Ul Hassan

Robin Karhu

Ivan G Ivanov

Nguyen Tien Son

Jer'onimo R Maze

Takeshi Ohshima

Oney O Soykal

Adam Gali

Sang-Yun Lee

Florian Kaiser

Jorg Wrachtrup
title: High fidelity spin and optical control of single silicon vacancy centres in silicon carbide
venue: Nature Communications
year: 2019

abstract: Optically interfaced spins in the solid state are a promising platform for quantum technologies. A crucial component of these systems is high fidelity, projective measurement of the spin state. In previous work with laser cooled atoms and ions, and solid state defects, this has been accomplished using fluorescence on an optical cycling transition; however, cycling transitions are not ubiquitous. In this work, we demonstrate that modifying the electromagnetic environment using an optical cavity can induce a cycling transition in a solid state atomic defect. By coupling a single Erbium ion defect to a telecom wavelength silicon nanophotonic device, we enhance the cyclicity of its optical transition by a factor of more than 100, which enables single shot quantum nondemolition readout of the ion's spin with 94.6% fidelity. We use this readout to probe coherent dynamics and relaxation of the spin. This approach will enable quantum technologies based on a much broader range of atomic defects.
author_names: Mouktik Raha

Songtao Chen

Christopher M Phenicie

Salim Ourari

A Dibos

Jeff D Thompson
title: Optical quantum nondemolition measurement of a solid state spin without a cycling transition
year: 2019

abstract: An ultrafast vector magneto optical Kerr effect (MOKE) microscope with integrated time synchronized electrical pulses, two dimensional magnetic fields, and low temperature capabilities is reported. The broad range of capabilities of this instrument allows the comprehensive study of spin orbital interaction driven magnetization dynamics in a variety of novel magnetic materials or heterostructures: (1) electrical pump and optical probe spectroscopy allows the study of current driven magnetization dynamics in the time domain, (2) two dimensional magnetic fields along with the vector MOKE microscope allow the thorough study of the spin orbital interaction induced magnetization re orientation in arbitrary directions, and (3) the low temperature capability allows us to explore novel materials/devices where emergent phenomena appear at low temperature. We discuss the details and challenges of this instrument development and integration and present two datasets that demonstrate and benchmark the capabilities of this instrument: (a) a room temperature time domain study of current induced magnetization dynamics in a ferromagnet/heavy metal bilayer and (b) a low temperature quasi static polar MOKE study of the magnetization of a novel compensated ferrimagnet.
author_names: Yu-Sheng Ou

Xinran Zhou

Rasoul Barri

Stephanie Law

John Q Xiao

Matthew F Doty
title: Development of a system for low temperature ultrafast optical study of three dimensional magnon and spin orbital torque dynamics.
venue: The Review of scientific instruments
year: 2020

abstract: Ultrafast Optical Control of Complex Quantum Materials Stefan Kaiser MPI Universitat Stuttgart Antrittsvorlesung It is well known fact that various phase transitions in condensed matter can by triggered by external parameters such as temperature, pressure, electric field or magnetic field. Finding systems that show phase transitions triggered by external stimulation of light became a particular interesting field of research. Advanced nonlinear optical methods such as ultra broad band pump probe spectroscopy open new ways of controlling ultrafast dynamics in complex solid state materials on unprecedented timescales. In quantum materials, finding new ways of manipulating the complex interplay of electronic phases or effectively tuning electronic interactions opens new avenues in controlling physical properties and designing new functionalities. Some of the most remarkable examples are stabilizing a transient superconducting state far above its equilibrium critical temperature. I will discuss how we investigate different scenarios like the balancing between competing phases triggered by ultra short light pulses or possibilities of dynamical stabilization of new states of matter in periodically driven light fields; thereby highlighting new methods we develop and new classes of materials that we explore. Gastgeber: Prof. Martin Dressel, Universitat Stuttgart, Telefon: 0711 685 64946
author_names: Stefan Kaiser
title: Ultrafast Optical Control of Complex Quantum Materials
year: 2018

abstract: The spatial alignment of the crystallographic axes of single colloidal quantum dots is determined by purely optical means. This capability allows maximizing the Zeeman interaction in a magnetic field which is vital e.g. for efficient and ultrafast single photon amplification.
author_names: Pascal Gumbsheimer

Christopher Hinz

Y Behovits

Florian Werschler

C Traum

Denis V Seletskiy

Alfred Leitenstorfer
title: All Optical Determination of 3 Dimensional Alignment of Crystal Axis of Single Colloidal Quantum Dots for Control of Ultrafast Spin Dynamics
venue: 2018 Conference on Lasers and Electro Optics (CLEO)
year: 2018

abstract: In order to have a better understanding of ultrafast electrical control of exchange interactions in multi orbital systems, we study a two orbital Hubbard model at half filling under the action of a time periodic electric field. Using suitable projection operators and a generalized time dependent canonical transformation, we derive an effective Hamiltonian which describes two different regimes. First, for a wide range of non resonant frequencies, we find a change of the bilinear Heisenberg exchange J_{\textrm{ex}}Jex that is analogous to the single orbital case. Moreover we demonstrate that also the additional biquadratic exchange interaction B_{\textrm{ex}}Bex can be enhanced, reduced and even change sign depending on the electric field. Second, for special driving frequencies, we demonstrate a novel spin charge coupling phenomenon enabling coherent transfer between spin and charge degrees of freedom of doubly ionized states. These results are confirmed by an exact time evolution of the full two orbital Mott Hubbard Hamiltonian.
author_names: M M S Barbeau

Martin Eckstein

Mikhail I Katsnelson

Johan H Mentink
title: Optical control of competing exchange interactions and coherent spin charge coupling in two orbital Mott insulators
venue: SciPost Physics
year: 2019

abstract: Electron and spin dynamics of strongly correlated NdNiO3 are investigated across the metal insulator transition with ultrafast optical spectroscopy at different temperatures, pump laser fluences, and laser polarizations. Transient differential reflectivity measurements on the insulating phase NdNiO3 show two characteristic electronic decay processes. The slow decay process, strongly dependent on coherent phonon excitation, is attributed to the electron phonon interaction, while the fast decay process, to the electron spin interaction. The temporal evolution of Kerr rotation reveals that net spin polarization can be induced by circularly polarized light in insulating NdNiO3 via electron excitation from the Ni t to e orbital, and two net spin polarizations with opposite directions are observed given the antiferromagnetic ordering in insulating NdNiO3. At the insulator to metal transition, the transient differential reflectivity reverses its sign; the metallic phase NdNiO3 also shows two characteristic electronic decay processes, a typical metallic decay processes and a slow decay process; the slow decay process is attributed to the interaction between electrons and the low frequency coherent phonons (2.45 THz) Our experiments demonstrate that the phase transition involves several processes upon continuous heating: the electron spin interaction disappears at 9 K below the transition temperature; at the transition temperature, NdNiO3 transitions into the metallic phase and the antiferromagnetic ordering transitions into the paramagnetic ordering; at the transition temperature, the structure of NdNiO3 changes from a monoclinic structure to a high temperature orthorhombic structure. Such a structure change results in the change in phonon vibrations, and subsequently, leads to the disappearance of the electron phonon interactions due to the insulating phase NdNiO3 and the emergence of other types of electron phonon interactions due to the metallic phase.
author_names: Weizheng Liang

Huaming Hou

Yuan Lin

S N Luo
title: Ultrafast electron and spin dynamics of strongly correlated NdNiO3
year: 2019

abstract: Mesoscopic ensembles of qubits offer a platform for near term applications in quantum technologies, as well as for studying many body physics. Key in exploiting these systems is the ability to coherently control constituent qubits in a manner that leaves the quantum states of neighboring qubits unperturbed. Atom like emitters in solids [1] have emerged as a promising platform for computing, communications, and sensing. In particular, their long coherence times, coherent optical transitions, and the ability to couple to nearby long lived nuclear spins make them excellent candidates for building medium scale registers of coupled qubits.
author_names: Eric Bersin

Michael P Walsh

Sara L Mouradian

Matthew E Trusheim

Kevin Chen

Tim Schroder

D Englund
title: Multi Qubit Registers of Individually Addressable Solid State Defect Centers
venue: 2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)
year: 2019