465 AUG 2017

No.

Paving the Way for the Information
and Communications Technology

No.465 AUG 2017

National Institute ofInformation and Communications Technology

CONTENTSFEATURE		 Paving the Way for the Information and		 Communications Technology

1

INTERVIEW

		 Establishing Advanced Technologies beyond
		 Extensions to Current Systems
		
Iwao HOSAKO

4 'Molecular State' of Artificial Atom and Photons
		New tool for quantum information technology

		Kouichi SEMBA / Fumiki YOSHIHARA / Tomoko FUSE

6 Spontaneous Formation of a Globally Connected		 Contractile Network in a Microtubule-motor System		Takayuki TORISAWA

8	Re-design of Biomolecular Motors Reveals Mechanisms

Generating Directional Motion under Thermal Agitation

		Ken’ya FURUTA

10 A Silicon CMOS Wireless Receiver in the 300-GHz Band		
Toward ultra-high-speed wireless communications technology using the terahertz band		

Shinsuke HARA / Issei WATANABE / Norihiko SEKINE / Akifumi KASAMATSU

TOPICS

12 NICT Intellectual Property -Series 5-

Area Monitoring System —Search utilizing the local community—		

13 Awards

Cover photo: "Microwave measurement system for superconducting quantum
circuits, incorporating dilution refrigerator"
A microwave measurement system used to explain new superconducting artificial
atom and photon states. Several microwave coaxial cables can be seen. To suppress
thermal excitation in the item being measured and make a precise measurementon the order of a single microwave photon, the superconducting quantum circuit
device is cooled by thermal contact with the minimal temperature plate (approx.
10 mK) of a dilution refrigerator.
The superconducting quantum circuit is extremely sensitive to magnetic noise so,
as shown in the photo in the upper left of this page, it is installed inside a two-layer
magnetic shield (silver colored cylinders) which attenuates external magnetic field
fluctuations by a factor of 1/1000 (fabricated in collaboration with NICT's Radio Wave
Management and Prototype Development Group).

Paving the Way for the Information and Communications Technology

Interview

Establishing Advanced Technologies beyond Extensions to Current Systems

ICT technology is currently producing
remarkable developments. However, many
issues that are difficult to resolve are manifesting with current technology such as increasing costs due to the explosive increase
in data volume and increasingly complex
security and control. The Advanced ICT
Research Institute takes a long-term perspective conducting R&D to address theseissues using innovative ICT technologies.
We spoke with Dr. Iwao HOSAKO, Director
General of the Institute, regarding the many
advanced research fields they are dealing
with at their two locations, in Kobe and in
Koganei (Tokyo).

Iwao HOSAKO

Director General
Advanced ICT Research Institute
After completing a doctoral program, Iwao
HOSAKO worked for NKK Ltd. (currently
JFE). In 1996, he joined the Communications
Research Laboratory, Ministry of Posts andTelecommunications (currently NICT). He
has been engaged in research and development of terahertz semiconductor devices
and various application systems.
Ph. D. (Science).

■ Playing pieces strategically for thelong game─ My image of the Advanced ICT ResearchInstitute is that it is cultivating new technologies for the future. Can you talk about whatsorts of systems and what research fields you
are working on?
HOSAKO: Broadly speaking, research at theAdvanced ICT Research Institute is composedof one laboratory, the "Frontier Research Laboratory," and three centers, the "Quantum ICT
Advanced Development Center," the "GreenICT Device Advanced Development Center,"and the "DUV ICT Device Advanced Development Center."
These Centers handle fields that are relatively close to being realized in society, or will be in
the foreseeable future. Of course, they are partof the Advanced ICT Research Institute, andas such, these technologies will still take sometime before they are fully deployed on a global scale. Even so, research results are steadily
accumulating, and the desire for some of thesetechnologies is growing. One such example isquantum cryptography, which will bring revolutionary advances that are urgently needed in
information security. Our three development
centers are dedicated to making progress inthese advanced fields.
On the other hand, the Frontier ResearchLaboratory handles themes that look farther
into the future than the Centers do. There aremany projects, but most of them are in the re-search areas of bio-ICT, nano-ICT, superconduction, and ultra-high frequency. Not all ofthese projects will necessarily be successful
in the future, but the themes have potential tobring great change that will revolutionize theworld. They are important, and truly at the frontiers of technology.
Our research is also advanced in terms ofscholarship, with approximately 35% of all
R&D related NICT press releases comingfrom the Advanced ICT Research Institute in
FY2016. The Advanced ICT Research Institutealso accounted for 20 to 25% of academic papers from NICT in the same period.
─ So your mission is to always look for the"seeds" of new technologies and to cultivate
them, isn't it?
HOSAKO: Around 30 years ago, Japan was
criticized as a "basic research free-rider," meaning that all we did was use basic research fromoverseas to do applied research and develop
products. Since then Japan, including researchby private enterprise, has focused activities
more and more on basic research. Even NICT's
predecessor, the Communications ResearchLaboratories (CRL) demonstrated advanced
basic research. By attracting excellent personnel and finding important themes for the future,they established the Kansai laboratory in 1989,
which became the foundation of the Advanced
ICT Research Institute of today.
Many of the research targets set at the time
have developed, expanded, and moved to other organizations. Examples include the natural
language translation research currently being
done at Keihanna Science City and brain networks and communications research being donein the center jointly operated with Osaka University. We expect that many results will growout of the Advanced ICT Research Institute in
the same way in the future.
We do not expect all of the research we areworking on to be useful on a global scale, but
if even one result has a large impact and grows
into a large research field in 20 or 30 years, wewill be able to look back and see the value of theAdvanced ICT Research Institute.

NICT NEWS AUG 20171

Paving the Way for the Information and Communications Technology

Interview

Establishing Advanced Technologies beyond Extensions to Current Systems■ Having a strong impact inboth device engineering andbiotechnology
─ What particular research subjects areyou focusing on in these two promising fields
for the future?
HOSAKO: There are some themes that we believe will have an especially large impact onsociety in the future.
Information and communication deals with
communication between nodes, but it is important to consider not just the communication
part, but also the information processing part.
Till now, information processing hardware hasdeveloped according to Moore's Law,* describing the miniaturization of circuits and increases
in performance. However, we are nearing thelimits of conventional development and a time
when we will have to utilize entirely new principles. We believe that various technologies
being cultivated at the Advanced ICT ResearchInstitute may be very applicable to this issue.
One such technology is in device engineering. The Advanced ICT Research Instituteis pursuing R&D on various types of devices
using optical, electronic, and superconducting
technologies. Several candidates have surfaced
to answer the question of which will be the bestfor next generation devices. These are footholds
to providing new material in fields like computer engineering and computer science.
Another area is that of bio-technology. Currently there is much attention on Deep Learning
approaches, which use neural networks withmulti-layer structure (modeling neural network structures in the human brain), and thisis producing real results. This originated froma biological perspective, initially learning fromthe overlapping layers and states of nerve structures, but even now it cannot be said that theseprinciples are fully understood. We take anapproach based on understanding, and believethat this type of approach is possible. There areseveral information processing mechanisms involved in biology, and if we can explain eachof them, we should be able to accomplish somevery interesting things.

＊ Moore's law
Moore's law is the observation that the number of components per integrated circuit doubles every year. Thislaw was described by Gordon Moore in 1965. Gordon wasa cofounder of Intel, a semiconductor manufacturer in the
United States.

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NICT NEWS AUG 2017

FigureOverview of the Advanced ICT Research InstituteOne example is analysis of insect brains,which is just getting started. The brain of a fruit
fly has approximately 200,000 neurons. That isfive orders of magnitude smaller than the caseof the human brain, with its tens to hundredsof billions of neurons, but it still has very advanced functionality. If we can understand how
it works from basic principles, we will be able
to build some extremely interesting and usefulsystems.
Till now, biotechnology has been focused
mainly in fields such as medicine and pharmacology, but in the future we see it more andmore as an area to learn from in engineering as
well.

■ Finding ways to integrate the ideas
of individuals into our mission
─ The Advanced ICT Research Institutehas locations in Kobe and in Koganei. How
are roles divided among them? And how do
you decide on research themes in anticipation of the future?
HOSAKO: Major themes are divided, with

nano-ICT and bio-ICT in Kobe and ultra-highfrequency and quantum ICT in Koganei, butrather than segregating them that way, it is morejust a matter of where the people involved arelocated.
Most of the themes at the Advanced ICT
Research Institute are based on ideas from individual researchers. We look far into the future,
considering various ideas and which ones will
become important. In this process, we cannot
overlook any ideas from individuals. This approach is quite unique to the Advanced ICT Research Institute, even within NICT, but it does
not mean we simply follow our own researchinterests. NICT is still ultimately committed tomission-based research. Our resources are also
by no means large, with a total of fewer than
200 researchers in both locations. Of course weneed to select and focus our efforts.
That said, selection and focus at the Advanced ICT Research Institute is characterized
more by asking "What sort of future will wework towards?" rather than simply, "Do this!
Don't do that!" This helps to align the directionsof researchers, naturally focusing resources sothat we can produce a strong impact, even withlimited resources. I feel that pointing out these
directions is also part of my role as the Director
General of the Institute.

NICT NEWS AUG 20173

Paving the Way for the Information and Communications Technology'Molecular State' of Artificial Atom and Photons
New tool for quantum information technology

his research began from asking the

T basic question,"What would happen
if coupling between light and an
atom was made extremely strong? " We haverealized extremely strong coupling using a
superconducting artificial atom, which hassimilar quantum properties to atoms, andmicrowave photons in a superconducting
circuit. We then found some very interesting
molecule-like states (ground states) in theartificial atom and photon.

Kouichi SEMBA

Executive Researcher
Frontier Research Laboratory
Advanced ICT Research InstitutePrior to joining NICT in 2013, Kouichi SEMBA
engaged in research on superconducting
quantum electronics at NTT Basic ResearchLaboratories, NTT Corporation, and at the
Global Research Center for Quantum Information Science of the National Institute ofInformatics. He is the Principal Investigatorof the Macroscopic Quantum Physics Project. Ph.D. (Engineering).

Fumiki YOSHIHARA
Senior Researcher
Frontier Research Laboratory
Advanced ICT Research Instituteresearch in fields related to these.
The Macroscopic Quantum Physics Project
was started in 2014 as part of this, and it has
used superconducting circuits to conduct research on the quantum properties of interactions
between light and matter. Superconducting circuits can be fabricated using semiconductor
micro-fabrication technologies, so a varietyof physical systems can be designed on small
chips that are only millimeters across.

■ Matter-light interaction andquantum nature■ Interaction between
superconducting artificial atom andphotons in microwave LC oscillators

In modern life, we make use of coupling
between matter and light everywhere, in lasers
and other devices. The blue light emitting diode, which led to the 2014 Nobel Prize in Physics, is one such example. We also often hear theword "quantum." One example is how, as laser
light is made very weak, the nature of photons(light quanta) begins to appear. Also, we eventually reach atoms as matter is divided smaller and smaller, and the energy of electrons is
known to be discrete (quantized) within atoms.
Using this unique quantum nature of photons
and electrons, future ICT technologies based oncompletely different principles have been conceived, such as quantum communication andquantum cryptography, and NICT is conducting

In this research, we have designed a circuit
using a superconducting magnetic flux quantum
bit (qubit) —which is also called an artificial
atom because, like an atom, it has discrete energy levels — and a photon inside a microwave
LC oscillator, such that they have deep strong
interactions (Figure 1). The state of superconducting flux qubit is a macroscopic electricalcurrent state with many electrons flowing in asuperconducting loop, so it produces a magnetic dipole moment that is orders of magnitude larger than that from the micro-electricalcurrent state of electrons in an atom. Also, byusing an LC oscillator designed to increase thezero-point fluctuation current, which is basedon the uncertainty principle in quantum me-

Tomoko FUSE

Senior Researcher
Frontier Research Laboratory
Advanced ICT Research Institute

References
1. F. Yoshihara, T. Fuse, S. Ashhab, K. Kakuyanagi, S.
Saito and K. Semba, "Superconducting qubit–oscillator circuit beyond the ultrastrong-coupling
regime," Nature Physics 13, 44 (2017).
2. T. Fuse, F. Yoshihara, K. Kakuyanagi, K. Semba,"Superconducting artificial atom and electromagnetic field interaction—beyond strong coupling—," to be published in the Nihon Butsuri
Gakkaishi (Butsuri) Journal of the Physical Societyof Japan.

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NICT NEWS AUG 2017

Figure 1 Superconducting
quantum bitmicrowave oscillator
coupled circuit

Figure 4 Schematic ground state of atom-photon
circuit under (a) no coupling,(b) deep strong coupling

Figure 2 Transition spectra of deep strong coupling
circuit (masquerade mask pattern*)
Horizontal axis is the magnetic flux bias energyof superconducting quantum bit , shownby frequency, and the vertical axis is thetransmission microwave frequency.

Figure 3 Dilution refrigerator (reachingtemperatures near 20 mK)
The lower 350 mm fabricated incollaboration with NICT's Radio
Wave Management and Prototype
Development Group* So named because of similarity to mask shapes in
Venice’s Masquerade Carnival.

chanics, we were able to realize for the firsttime a deep strong coupling state in which theinteraction energy between the quantum bit andmicrowave photon exceeded the transition energy of quantum bit or microwave photon itself.
We also successfully measured the absorption
spectra of the state (Figure 2). A dilution refrigerator was used in the measurements to cool thesample to approximately 20 mK, so that the absorption of a single microwave photon could bediscriminated (Figure 3).

■ Deep strong coupling
So, what can happen in a deep strong coupling regime? Consider the ground state (lowest
energy state) of an atom-photon coupled system. When there is no coupling between atomand photon, their states can be considered independently.
Individual photons have energy, so no photons are in a ground state. The ground state of
an atom is expressed when the atom's up-spinand down-spin are superimposed (spin is the
direction of magnetic moment) (Figure 4(a)).
When coupling increases into the deep strong
coupling regime, the ground state, the blue-photon-dressed states* of spin up and red-photondressed state* of spin down are superimposed(Figure 4(b)). In other words, rather than there
being no photons in the ground state, when
the atom is spin up, the photons always takeon blue, and when they are spin down, they
always take on red. Thus, there is strong correlation between the atomic states and photons,
and this superposition state (quantum entanglement between atom and photon; similar to the
Schrödinger's cat-like state) is the ground state.
Generally, quantum entangled states arequite fragile, but the quantum entangled groundstate generated in deep strong coupling is not
excited states, so this state can be expected to
be much more stable.

■ Conclusion
Quantum entanglement is an important resource for quantum information processing andquantum ICT, and recent expansion into basic
science and measurement applications is promising, including attempts to apply multi-photon
entangled states for quantum enhanced sensing.
Deep strong coupling states have just been dis-covered, but there is on-going research on applications of such "Schrödinger's cat" states inquantum information processing and quantum
enhanced sensing. Interested persons can referto the original paper1 or the explanatory article
in Japanese.2* Spin dresses phase-aligned virtual photons. Taking spin-up
dressed photons as having phase of 0 (shown in blue), spindown dressed photons will have phase of π (shown in red).

Project members
Front row from the left:
Ziqiao AO (collaborating
researcher), Yuya YONEZU(collaborating researcher),
Tomoko FUSE (SeniorResearcher)
Back row from the left:
Kouichi SEMBA, Fumiki
YOSHIHARA (SeniorResearcher), Akiko HOSHI

NICT NEWS AUG 20175

Paving the Way for the Information and Communications Technology

Spontaneous Formation of a Globally Connected Contractile Network
in a Microtubule-motor Systeme have discovered various networks

W formed by microtubules, a kind ofcytoskeletal protein, and kinesin, amolecular motor operating on them, andthe ability of these networks to cause an
overall contraction. We have also createdmathematical models able to explain theirdynamics quantitatively. Simulating cytoskeleton dynamics in vitro (in a test tube)
and in silico (in a computer) is promising fordevelopment of technology to change cellfunction and cell organizational structure
more easily.

■ Various structures and dynamics
observed within cells

Takayuki TORISAWA
Researcher
Frontier Research Laboratory
Advanced ICT Research Institute

After receiving Ph. D. degree in 2014,
Takayuki TORISAWA joined NICT. Since
then, he has been engaged in research on
the regulatory mechanisms of molecularmotors, collective motion, and self-organization in motor-cytoskeleton systems.
CREST Researcher (Creation of Fundamental
Technologies for Understanding and Control of Biosystem Dynamics). Ph. D. (Arts andSciences).

Living things are all composed of cells. Cells
move and change their shape dynamically in response to external stimuli and perform various
biological activities. These dynamic changes
in cell structure are accomplished by the cytoskeleton, including actin protein filaments andmicrotubules, and various proteins that connect
them (Figure 1A). The cytoskeleton produceschanges by changing shape and length of filaments through polymerization and depolymerization, and also through movement of proteinsconnecting the filaments. Well known major
cytoskeletal functions include material transport rails inside the cell, and the mitotic spindles(microtubules) and contractile ring (actin) thatform during cell division (Figure 1B). Besides
these, plant cells, muscle cells (myocytes), andtracheal epithelial cells have mesh-like network

structures of microtubules that work to maintainthe shape of the cells (Figure 1C). There has
been very little previous research on the formation of such networks and their dynamics relative to research on structures such as the mitotic
spindle. As such, the goal of this research has
been to explain the mechanisms of dynamics inthese sorts of network structures.

■ Various network dynamics
emergent by combining two typesof element
Inside real cells, many proteins interact witheach other to bring about complex biologicalphenomena. One way to identify the elements
and properties needed for a given complex
phenomenon is to reconstruct a coarse-grained
system. More concretely, a simple system composed of a few elements that are expected to beneeded is prepared and then comprehensively
observed and modeled to gain a deeper understanding. In this research, we built a system tounderstand the dynamics of cytoskeletal network structures consisting of only microtubules
and a type of protein molecular motor calledkinesin. There are many types of kinesin, and45 types of kinesin genes in humans. We used atype called kinesin-5. Kinesin-5 has four motor
domains (which connect with microtubules andare the primary parts handling mobility), andcan form network shapes by bundling multiple
microtubules. By moving along the microtubules, they also cause sliding motion among the
microtubules within a bundle, causing dynamic

Figure 1 Various structures created in a cytoskeleton and their movement
A: Cytoskeleton in an animal cell (actin and microtubule) in interphase
B: Cytoskeleton in a somatic cell when it is dividing
C: Microtubule network observed in plant cells

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Figure 2 Molecular motor used in experiments (kinesin-5); structure andfunction

Figure 3 Various patterns created by kinesin-microtubule mixed system and agraph showing their dependency on density of elementschanges in the network (Figure 2). We mixed
kinesin-5 and microtubules in various concentrations and conducted comprehensive observations of the resulting dynamics (Figure 3).
Figure 3 shows that when kinesin-5 concentration is low, networks are formed but there is nochange to the overall structure (static network).
As the concentration of kinesin-5 is increased,
microtubule networks slowly start to contract
after they form. Soon some begin to break,and a transition to a sudden contraction occurs(active network). If kinesin-5 concentration
is increased further, there are localized strong
contractions and division into clusters of various sizes (aggregation). These sorts of network
contraction depend on motor concentration andmechanical characteristics, and we confirmedthat by changing the motor properties, small radially extended microtubule structures (asters)
distributed uniformly over the whole observation area formed.

Figure 4 Mathematical model overview and comparison with experimental
results
A: Network coarse-graining
B: Three localized rules in the model
C: Comparison between experimental results and simulation■ Creating mathematical models to
explain network dynamics
Based on our comprehensive observationsof network dynamics in systems combining
kinesin and microtubules, we constructed acoarse-grained model to identify the essential
elements of the phenomena. The theoreticalmodel was built in collaboration with the groupof Associate Professor Shuji ISHIHARA of the
Science and Technology Department of Meiji
University (currently Associate Professor at
The University of Tokyo), and we were able
to reproduce the observed experimental results(static network, active network, aggregation,
and aster formation) with a network model
specifying only three local rules (Figure 4). It
also showed great promise in predicting the effects of changing motor characteristics on network structure.

and function of tissues, which are groups ofcells. We were able to show the potential for
great changes in cytoskeleton dynamics bychanging only concentrations and motor characteristics in simple systems consisting of only
two types of protein. By successfully modelingit mathematically, we also hope to contribute totechnical developments that enable cell function and structure to be changed more easily.

■ Future prospects
Cytoskeleton dynamics affect not only cell
shape and behavior; they also affect the shape

NICT NEWS AUG 20177

Paving the Way for the Information and Communications Technology

Re-design of Biomolecular Motors Reveals Mechanisms Generating
Directional Motion under Thermal Agitation

he Frontier Research Laboratory has,

T for the first time, successfully cre-ated artificially designed new biomolecular motors. These new motors were
implemented based on dynein,*1 a type of
biomolecular motor, fused with anotherfunctional module also existing in nature.
We were also able to fabricate molecularmotors that move in the opposite direction.
These results are very promising for use as adesign principle for artificial molecular machines that function efficiently in the presence of vigorous thermal agitation, which isunavoidable at the nanometer scale.

■ Background

Ken’ya FURUTA

Senior Researcher
Frontier Research Laboratory
Advanced ICT Research Institute
After completing graduate school, Ken’ya
FURUTA became a Research Fellow of theJapan Society for the Promotion of Science,and then joined NICT in 2009. Senior Researcher since 2013. Engaged in research on
design and fabrication of protein nanomachines. Ph.D. (Arts and Sciences).

A young genius gathers countless “Microbots” together to create a large structure whichmoves around the town freely. Such a scenario appeared in the computer animation movie
Big Hero 6, released in 2014, and it shows how
small machines that can only perform simple
movements on their own can be made to perform large, complex tasks when gathered together. This idea has often been depicted as the
future of artificial machines.

■ What are molecular machines?
This sort of idea is becoming a major trend
in the world of science and technology. In fact,
the 2016 Nobel Prize in Chemistry was awarded for research implementing nanometer scale
switches and bearings using organic moleculesand chemical synthesis technology and producing work and power by manipulating extremely
small molecules. This type of technology is stillat the basic research stages, but it has potential
for huge impact on real society in the future.
Since the industrial revolution, artificial machines have been made with great success basedon a paradigm of correct operation through topdown control systems. However, much attention has recently been placed on the search foralgorithms used by living organisms. For example, there is much activity developing new machines with many elements performing distributed processing, taking hints from the way treeschange their shape adaptively, and from the autonomous distributed systems of ants (McEvoy
et al., Science 2015, etc.). Existing top-down
networks are showing weakness after weakness, such as vulnerability to pin-point attacks
and the difficulty in making large-scale changes
to networks, the bottom-up survival strategies
from biology used in these systems provide agood counter-proposal for consideration.

■ Life already has extremely
functional molecular machines
In living organisms, there are systems at
all levels that very naturally perform incredibly advanced distributed processing from ahuman perspective, from the level of ant societies, to individuals, biological tissues, anddown to the cell level. At the cell level, mostmuscle, spindle, cilia and flagella cells, havenanometer scale molecular machines made ofproteins, called biomolecular motors, that workon filaments extending throughout the cells.
These produce cooperative phenomena such as
contraction, elongation, and oscillatory motion
on a scale of a centimeter or more, six to eightorders of magnitude larger than the motors

Terminology＊1 Dynein
A type of biomolecular motor that works inside
cells. It is a protein complex that moves along
microtubules featuring a clear modular structure, with a ring-shaped motor domain and a
microtubule bonding site that protrudes fromthe ring.
＊2 ATP hydrolysis activity
Biomolecular motors such as dynein use adenosine triphosphate (ATP), which serves as theenergy currency in cells, as the driving force. The
major structural changes accompanying hydrolysis of ATP is very important for unidirectionalmotion.

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Figure 1 Newly designed biologicalmolecular motor. The microtubulebinding site is removed fromdynein, and an actin-binding site
is combined with the dynein motor
domain.

Figure 2 Total internal reflection fluorescence microscope image of the
new molecular motor fixed to a glass surface. How actin filaments
are moved is shown. The video is processed, with a different color
applied to actin filaments for each time frame to show motion of
the filaments.

themselves. Obviously, such collective behavior is all programmed into the properties of theindividual molecular machines. In contrast tohuman-made machines, this truly is bottom up
control, with no commander.
Biomolecular motors perform most biological work with directed motion, such as muscles
and dividing cells, and they work in the microscopic world of only tens of nanometers in size;
only one thousandth of the thickness of a humanhair. This world shakes vigorously, with sometrillion collisions per second due to the motionof thermally agitated water molecules, so operation of these biomolecular motors is analogous
to driving a car to your destination through astorm full of tornados.
Currently, it would be impossible to build amolecular machine from scratch that could operate under such conditions. There are technicaldifficulties, but even before that is the problemof establishing the most basic principles forwhat a reasonable design could be. In the way
artificial macroscopic machines are usually designed, random thermal agitation is considered
to be noise, and a large amount of energy isused to suppress it. On the scale of molecularmachines, however, thermal agitation is muchlarger than the energy that can be expended permolecule so it cannot be ignored.

■ Understanding design principles forcreating new biological molecularmachines
With research analyzing just existing biomolecular motors, which are a result of the unique
history of life, it has not been easy to close inon the essence of unidirectional motion at the

Figure 3 A total internal reflection fluorescence microscope is an optical
microscope that enables visualization of fluorescence of single
molecules. Near-field light emitted from the glass surface is used
for illumination and to suppress background light.

nanometer scale, even if we have been able tounderstand structure or function when applied
to particular life processes. One effective way
to clarify these principles, in addition to analyzing existing biomolecular motors, could be
to take a constructive approach where desired
functionality is achieved by combining various
elements with simpler functionality.
According to the above-mentioned approach, we used the motor domain of a typeof biomolecular motor called dynein as a motor core, and actin-binding domains for filament binding instead of the original microtubule-binding domain of dynein (Figure 1).
If, as has been conventionally thought, theinterface with the rail had to be tightly coupled with the ATP hydrolysis activity*2 of the
motor core, then introduction of a completely
unrelated actin-binding domain would be expected to simply cause loss of motility. However, contrary to expectation, the new molecularmotor was able to translocate an actin filamentsmoothly in one direction (Figure 2). We gathered detailed data on the correspondence between direction of motion and structure using
a total internal reflection fluorescence microscope (Figure 3). We thus proposed the possibility that these biomolecular motors do not
overcome the turbulence of thermal agitation,
suppressing it by precisely matching the timing of enzymatic activity and filament binding/unbinding functions. Rather, they implement
motion based on a simple mechanism that relies
only on asymmetry in the structure of the interface to rectify the random motion of thermal agitation into one direction. This type of approach
will rule out mysterious mechanisms that arefound everywhere in biological sciences, andreveals the potential to access essential designprinciples for what materials are needed andhow they are arranged in order for molecularmachines to function.

■ Future prospects
Research on designing new molecular machines with a desired function has just begun,
but our research has already revealed a direction to some extent. In the future, we intend tocreate new artificial molecular machines basedon those that give motility to living things,
thereby explaining design principles, and creating highly-functional autonomous molecularmachines that even surpass those derived fromliving things.

NICT NEWS AUG 20179

Paving the Way for the Information and Communications Technology

A Silicon CMOS Wireless Receiver in the 300-GHz Band
Toward ultra-high-speed wireless communications technology using the terahertz band

esearch and development of tera-

R hertz wireless communication cir-From the left: A. KASAMATSU, S. HARA, I. WATANABE,
N. SEKINE

Shinsuke HARA

Senior Researcher
Frontier Research Laboratory
Advanced ICT Research Institute
After completing graduate school, Dr. HARA
was Assistant Professor at Tokyo Universityof Science, Faculty of Industrial Science andTechnology before joining NICT in 2013.
Engaged in research on millimeter-wave
and terahertz-wave CMOS circuits andnano-electronic devices. Ph. D. (Science).

Issei WATANABE

Senior Researcher
Frontier Research Laboratory
Advanced ICT Research Institute

Norihiko SEKINE

cuits in the 300-GHz band, which has
not yet been allocated or used, using silicon
CMOS technology was done in cooperation
with Hiroshima University and Panasonic
Corporation. A 300-GHz CMOS transceiver
operating above the unity-power-gain frequency of CMOS was realized by developing
several innovative circuit technologies, anda wireless link with the high data rates using
multi-level modulation was demonstrated.

■ Introduction
Electromagnetic waves, including radio
waves and light, are used broadly in industrial fields. Radio wave frequencies are allocatedaccording to specific uses under the relevant
regulations. Radio waves up to frequencies of
30 GHz are in general use, but with the proliferation of smartphones and other information
terminals, radio resources are becoming depleted. The industry is also now entering a newphase of restructuring due to the evolution of
the Internet of Things (IoT), Big Data, and AI,

Research Manager
Frontier Research Laboratory
Advanced ICT Research Institute

Akifumi KASAMATSU
Executive Researcher / Associate
Director of Frontier Research Laboratory
Advanced ICT Research Institute■ 300-GHz silicon CMOS wirelesstransceiver

Figure 1 Atmospheric attenuation and frequency
allocation in 300-GHz bands (below) andpossible applications of terahertz wirelesscommunication (above)

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and wireless communication technology will
increasingly play a major role. It will be essential to achieve wireless technologies capable ofhigher capacity and higher speed communication, and to do so, new radio resources must be
exploited.
Millimeter- and terahertz (THz) waves areelectromagnetic waves that occupy the range
between radio and light, with wavelengths from10 to 0.1 mm and frequencies from 30 GHz to
3 THz. They are not yet being utilized muchand are an unexploited frequency band. Figure
1 shows the atmospheric attenuation characteristic in the low THz frequency range. The
wide portion of the electromagnetic spectrum
that can be transmitted with less distortion orabsorption, which is called the "atmosphericwindow," occupies the frequency range from
182 to 325 GHz. The band above 275 GHz has
not been allocated at all, and discussion regarding its utilization has begun in international
standards organizations. If a wide band in thisrange could be secured and wireless communication implemented using multi-level modulation, which can transmit multiple values on one
signal, high speed wireless communication over
100 Gbps would be possible. This would be
more than ten times faster than speeds anticipated with fifth-generation (5G) mobile communication systems that will use the 28-GHz band.
Realizing such ultra-high-speed wireless communication technology would make possible
applications such as those shown in Figure 1.

Silicon CMOS technology for constructing
integrated circuits with millions or hundreds ofmillions of transistors is used in digital processing and memory circuits. To achieve broad useof ultra-high-speed wireless communicationin the THz band, it would be desirable to also
realize wireless communication circuits (i.e.,transceivers) using silicon CMOS technology,
so they can be integrated with digital processing
and memory circuits. However, the unity-power-gain frequency (fmax), which is where theunilateral power gain rolls off to 1 (0 dB), isapproximately 280 GHz for silicon CMOS transistors, which is not adequate for the wirelessInterstage matching circuit
Amplifier stage
Amplifier stage

Amplifier stage
Interstage matching circuit

Figure 2 Block diagram of (a) typical and (b) proposed wireless receiver, (c) chip micrograph of the 300-GHz CMOS
receiver, (d) its performance characteristics, and (e) constellations from wireless communication tests

communication carrier frequencies of 300 GHz
that we hope to achieve. Since only signals at
frequencies below fmax can be amplified, an amplifier for wireless communication in the 300GHz band cannot be designed using silicon
CMOS technology.
Recently, we presented 300-GHz silicon
CMOS transceivers that resolve the above problem using several circuit technologies in collaboration with Hiroshima University and Panasonic Corporation. A wireless receiver which
receives radio frequency (RF; 300-GHz bandin this case) signals converts them to a lower
frequency suitable for processing to recover
the information. The received signals are weak
and buried in noise, so normally an architecture with a low-noise amplifier to amplify theRF signal placed after the antenna is adopted.
However, the 300-GHz band RF signal cannot
be amplified using silicon CMOS transistors
as explained above. Therefore, we adopted anarchitecture with a frequency converter (mixer) at the first stage. This mixer mixes the RF
signal with a local oscillator (LO) signal of frequency upconverted to a frequency similar to
the RF signal, converting to a signal of several
GHz. To prevent the signal from being buried
in noise, the noise figure must be reduced andthe conversion gain of the initial mixer maximized, requiring a high LO signal power in the
300-GHz band. A frequency multiplier circuit
able to generate a high-output LO signal was
designed, which enabled implementation of ahigh-conversion-gain receiver. The receiverachieved a high wireless data rate of 32 Gbps
in the 300-GHz band using a multi-level modu-

lation scheme in wireless link evaluation with asilicon CMOS transmitter that was developed at
the same time (Figure 2).

■ Circuit elements for implementing awireless transceiver
In our silicon CMOS transceiver circuits,
300-GHz band signals are generated by upconverting (multiplying) intermediate frequency (IF) signals at frequencies from 100 to 150
GHz at the last stage. To generate high power in the frequency converter or multiplier,a high-power, high-gain amplifier with wide
bandwidth is needed in the IF band. The amplifier is composed of transistors, but the gain andbandwidth of a single transistor is limited, so
a cascade connection of several amplifier stages is used to increase the bandwidth and gain.
The impedance is different at the outputs andinputs between the cascaded connected stages,
so inter-stage matching circuits are also needed to transfer the signal smoothly, without loss
or reflection. However, such matching circuits
occupy large area when implemented with conventional techniques, which seriously increases
development and production costs. To resolve
this problem, we developed a circuit layout
technique to reduce the matching circuits tominimal dimensions. The technique enabled thesize of differential amplifier to be reduced andimplementation of high gain with wide bandwidth (Figure 3).
The silicon CMOS wireless transceiver
which demonstrated the feasibility of THz
high-speed wireless communication was im-

Figure 3 Schematic diagram of(a) conventional and (b) proposedinter-stage matching circuit ofdifferential amplifier, and (c)small signal characteristics of the
proposed amplifier

plemented by adapting this technique as well as
several newly developed techniques including
a cubic or square mixer and power divider andcombiner .

■ Future prospects
In the future, we will improve the characteristics of our silicon CMOS wireless transceiver,continue development of related basic elemental technologies, and develop modules. In thisway, we aim to soon realize ultra-high-speed
wireless communications using 300-GHz band
terahertz signals with silicon CMOS integrated
circuits.
A part of this research was conducted as partof Ministry of Internal Affairs and Communications R&D to expand radio frequency resources entitled, "R&D on Terahertz Signal Device
Basic Technology: 300-GHz band silicon semiconductor CMOS transceiver technology."

NICT NEWS AUG 2017

11

NICT Intellectual Property -Series 5-

Area Monitoring System ―Search utilizing the local community―
Businesses are already being developed using GPS systems to look for elderly persons, children, or others needing monitoring, but there is potential for even more rapid, reliable monitoring utilizing IoT in
traditional local communities. We introduce an area monitoring system based on a new idea, using new
wireless systems that will be common in the future, and recruiting local collaborators as human resources.
■Technical overview and application fieldcording to the conditions and providing information about a

Monitoring systems using GPS can find locations anywhere

possible encounter with the person being monitored reducesin the world, but they are not able to find locations indoors,

the burden on the collaborators and increases the probability

where the GPS satellite signals do not reach. To overcomeof finding the missing person. If the missing person is found,

this problem, various indoor positioning systems have beenfamily and other search collaborators are notified.

developed, but indoor and outdoor systems are different sothere is no single system to solve the problem. The service ar-■ Quest for uses, applications, and collaboration partners

eas provided by the above-mentioned systems do not always

We envision using Wi-SUN, which is expected to expand

agree with what is needed for monitoring and the monitoring

throughout Japan soon, for positioning and communication

accuracy.

in this monitoring system. If a beacon from Wi-SUN, which has

For our monitoring scheme, participants from the area

a short range, is received, the location of the Wi-SUN device

monitoring community are registered beforehand as search

can be used as the location, whether indoor or outdoor. Thus,

collaborators, along with their usual daily activities. Then, when

the rough location of the person being searched for is known,

search is needed for a person being monitored, these data areeven without using a location from GPS or other system, andused to predict the behavior of each of the search collabora-

the device carried by those being monitored, which must run

tors. Search collaborators are further narrowed down based on

on batteries, can be compact and low power. NICT is planningtheir current location. Based on a real-time prediction of theirdemonstrations to verify the effectiveness of this technology.

activities, they are notified that they could encounter the per-For further information, please contact our office at ippo@

son being monitored. Thus, selecting search collaborators ac-

ml.nict.go.jp as shown below.

Figure Area monitoring
system<Patent information><Contact (Inquiries, etc.)>

Publication No.: Patent Pub 2017-116980

Intellectual Property Promotion Office, Innovation Promotion

Name of invention: Area monitoring system

Department
E-mail:
TEL: +81-42-327-6950 FAX: +81-42-327-6659

12

NICT NEWS AUG 2017

The Minister of Education, Culture, Sports, Science and Technology Prizes are given to persons who have achieved
notable results in R&D or in advancing understanding in fields of science and technology. The Ichimura Prize ispresented to technical researchers or groups conducting research at a university or a research institute that hascontributed to advancement in a scientific field and has research achievements with practical applications.

Minister of Education, Culture, Sports, Science and Technology

FY2017 The Commendation for Science and Technology
by the Minister of Education, Culture, Sports, Science and Technology
Research Category, Prizes for Science and Technology
Masahide SASAKI

Mikio FUJIWARA

Distinguished Researcher,
Advanced ICT Research InstituteResearch Manager, Quantum ICT Advanced
Development Center, Advanced ICT Research InstituteComment from the Recipients
I am very honored to receive such a prestigious award. I am receiving it on behalf of themany others within and outside of NICT whowere also involved in this R&D. I have been so
fortunate to be able to conduct basic and appliedresearch and development in such a world-classenvironment, supported and encouraged by suc-cessive management and my seniors at MIC and
NICT, and working with such wonderful colleagues. I hope to continue working with thesewonderful colleagues, bringing more dreams toreality.

data● Date: April 11, 2017
● Description: Research demonstrating
quantum information andcommunications and its applications

Young Researcher Prize
Taro YAMASHITA
Senior Researcher, Frontier Research Laboratory,
Advanced ICT Research InstituteComment from the Recipient
I am very honored to be recognized for research results in superconducting single photon
detectors (SSPD) at NICT. SSPDs are a technology that is already receiving attention in many
fields such as quantum science, life sciences,and space applications. Further performanceadvances in the future are anticipated to expand

the range of applications as well. I would like tothank my family, my laboratory colleagues, andother collaborating researchers for their constantsupport and will continue efforts to advance research on superconducting quantum devices.

data● Date: April 11, 2017
● Description: Research advancing superconducting photon detectors
and applications in quantum
and life sciences

The New Technology Development Foundation

49th The Ichimura Prize in Science for Distinguished Achievement
Shinji NISHIMOTO
Senior Researcher, Information and Neural Networks Laboratory
Center for Information and Neural Networks

Comment from the Recipient
I am honored to receive this award in recognition of our work to build a quantitative framework for analyzing human brain activity during
complex natural audiovisual experiences, andfor showing the potential for its applications inreal society.
I would like to express deep gratitude to all
who gave me direction and support in this work,
both directly and indirectly. Encouraged by thisrecognition, I will continue to devote myself toadvancing excellent research.

data● Date: April 26, 2017
● Description: Development and applicationof brain modeling and decoding technology

Center: Shinji NISHIMOTO, Right: Mrs. NISHIMOTONICT NEWS AUG 2017

13

NICT NEWS No.465 AUG 2017

Published by
Public Relations Department,
National Institute of Information and Communications Technology<NICT NEWS URL> http://www.nict.go.jp/en/data/nict-news/

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