01

Message from the Director

We at NTT Basic Research Laboratories (BRL) are extremely
grateful for your interest and support in our research activities
during the last year.
Our laboratories central mission is to promote breakthroughin science and innovations in leading-edge technology that canadvance NTT's long-term business, overcoming current limitationsin speed, size, and of course energy consumption.
To achieve this, our scientists & engineers in the fields of physics,
chemistry, biology, mathematics, electronics, informatics, andmedicine, conduct fundamental research in material, physical, andquantum science.
An "open door" management policy allows us to collaborate
with many universities and research institutes from all over
the world, as well as other laboratories within NTT, further
enhancing our ability to achieve our missions. We have regularlyorganized international symposiums and workshops at our Atsugi
R&D center to disseminate our research achievements andcommunicate with fellow scientists, engineers and the public.
During the coronavirus pandemic, we have been transmitted our
research activities and results via networks, but in this "newnormal" age, we would like to explore ways to take advantage ofthe strengths of virtual, online and on-site communication. We arealso resuming face-to-face discussions while watching closely tothe coronavirus situation.
All of these activities enable us to realize our "open door" policy
and mission.
Your continued support would be highly appreciated.

Dr. Kazuhide Kumakura
Director of NTT Basic Research Laboratories,
Nippon Telegraph and Telephone Corporation

02

Activity Report

Advisory Board
The aim of the Advisory Board is to provide
a critical and objective evaluation of ourresearch plans and activities. This enables
us to employ strategic management ina timely manner. Proposals and advice
received at this biennial board meeting arereflected in our actual ongoing researchand its management. The 12th meeting will
be held on-site in February, 2023 and weare planning to report our latest research
results and received valuable feedback.

ISNTTInternational Symposium on Novel maTerials andquantum Technologies

The International Symposium on NovelmaTerials and quantum Technologies(ISNTT) focuses on the latest developments
in materials science, applied physics, andquantum physics for future technologies. Thisbiennial symposium brings together world
leading academics, scientists, and students
with our NTT BRL researchers to foster
interactions, discussions, and collaborations.
It will be our pleasure to hold this meeting
physically in Atsugi for the year 2023.

N T T- B R L S c h o o l
The NTT-BRL School’s mission is to foster the development of young researchersand promote the international visibility of NTT. Since 2017, the school has been held
alongside ISNTT, enabling those young researchers to directly interact with world
leading experts in the field. However, the ISNTT2021 virtual format made this extremely
difficult to achieve and so the school was postponed. We look forward to resuming the
NTT-BRL School in conjunction with the ISNTT to be held onsite in 2023.

Front image:

Optical-to-Electrical Conversion
in Graphene
Graphene has attracted significant interest
due to its potential to outperform existing
semiconductor devices with its high sensitivity
and fast electrical response to broadband light.
We achieved a breakthrough by developing theworld’
s fastest zero-bias graphene photodetector
through the combination of optimized device
structure and advanced measurement techniques.
As we move forward, we aim to enhance theperformance of this device by incorporating avariety of two-dimensional atomic layer materials,
thereby unlocking its full potential and breaking
conventional limitations.

03

Organization

NTT Basic Research Laboratories

Director

Kazuhide Kumakura

Research Planning Section

Multidisciplinary Materials Design and Science Laboratory

Advanced Applied Physical Science Laboratory

Quantum Science and Technology Laboratory

Executive Manager

Executive Manager

Executive Manager

Executive Manager

Katsuya Oguri

Hideki Yamamoto

P5●Nanodevices Research

Research Group●Low- Dimensional
Nanomaterials Research
Group●Molecular and Bio Science
Research GroupGroup●Nanomechanics ResearchGroup●Quantum Optical Physics
Research Group●Photonic Nano-Structure
Research Group●Researchers (Foreign Researchers)…98（１0）●Research Associate/Specialist…7●International Interns…19＊●Domestic Interns…18＊●Guest Researchers…2＊

P7●Thin-Film Materials

The population data of NTT-BRL members●Joint Researcher…7

Katsuya Oguri＊…Jan. to Dec. 2022 total

Hiroki Takesue

P9●Quantum Optical State

Control Research Group●Theoretical Quantum

Physics Research Group●Superconducting Quantum

Circuits Research Group●Quantum Solid State

Physics Research Group04
As of Dec. 31, 2022

Advisor y Board

Chalmers University of Technology, Sweden

Max-Planck-Institut für Festkörperforschung,Germany

University of Illinois at Urbana-Champaign,USA

Imperial College,UK

Université Pierre et Marie Curie,France

The University of Texas at Austin,USA

Forschungszentrum Jülich, Germany

CEA Saclay, France

University of Twente, Netherlands

Prof. Per Delsing

Prof. Sir Anthony J. Leggett

Prof. Klaus von Klitzing

Prof. Sir Peter Knight

Prof. Elisabeth Giacobino

Prof. Andreas Offenhäusser

Prof. Allan MacDonald

Prof. Christian GlattliProf. Dave H.A. Blank

Nanophotonics Center

Research Center for Theoretical Quantum Physics

Bio-Medical Informatics Research Center

Project Manager

Project Manager

Project Manager

Masaya Notomi

P11

William John Munro

P11

Hiroshi Nakashima

P11

Research Professors

Sakakibara Heart Institute, Advisor

Tohoku University

University of Toyama

Prof. Hitonobu Tomoike

Prof. Masao Morita

Prof. Kiyoshi Tamaki

Tohoku University, Professor Emeritus

Hiroshima University

Prof. Junsaku Nitta

Prof. Hideki Gotoh

05

Multidisciplinar y Materials Design and Science Laborator yGroups and Research Themes

Multidisciplinary Materials Design andScience Laboratory
Overview
T h e a i m of t h e M u lti d is c i p li n a r y M a te ri a l s D e s ig n a n d
Science Laboratory is to contribute to progress in materials
science a n d to revolutio nize informatio n commu nicatio ntechnolog y by creating novel materials with various
internal degrees of freedom (lattice, charge, spin, orbital,etc.) through materials design and synthesis beyond
c o nve n ti o n a l c o n c e p t s of c l a s s if i c a ti o n s , d i m e n s i o n s ,scales, and synthesis methods. The research groups that
constitute this laboratory are investigating a wide rangeof materials including semiconductors, superconductors,
m a g n e t i c m a t e ri a l s , t o p o l o g i c a l m a t e ri a l s , c o n d u c t i v epolymers, and biological soft materials. We are conducting
innovative materials research based on advanced thin-filmgrow th te ch n ologies , high - p re cisio n a n d high - resolutio nmeasurements of structures, properties along withtheoretical studies, and data science (informatics).

Multi-source molecular beam epitaxy apparatus:
an enabling technology for high-quality thin films
of complex oxides/nitrides, which is also exploited
as a synthesis method sui generis for novel
superconductors and magnetic materials.

Thin-Film Materials Research Group
Novel Semiconductor Devices

Creation of light- emitting devices over a wide range from
D U V to N I R , high - ef ficiency energ y conversion devices ,hig h - p owe r d evic e s , a n d n ovel m ultif u n ctio n al (o ptic al,
electric, and spintronic) devices

Low-Dimensional Nanomaterials ResearchGroup
2D atomic-layer Materials

Creation of ultimately thin functional atomic-layer materials
for next-generation electronics

Complex Oxide Thin Films

C re a tio n of t ra il b la zi n g s u p e rc o n d u cto r s a n d m a g n etic
materials beyond conventional concepts

Molecular and Bio Science Research Group
Biocompatible Electrode Materials

Development and application of bioelectrode materials formeasurement of deep biological information

Bio-devices
Creatio n of bio -fu n ctio nal mim etic d evices exploiting
biomolecules, cells, and soft materials

06

Achievements in 2022

0

AlGaN:Si
graded AlGaN:Si

10

AlN:Si

10

-4

10

-6

10

-8

500°C
400°C
300°C
200°C
100°C
RT

d

10

-10

10

-12

10

-14

10

-20

-15

-10

-5

DrainVvoltage(V)
gd (V)

0(Left side) Schematic view and optical microscope image of AlN-basedtransistors.
(Right side) Transfer characteristics at different temperatures from room
temperature to 500°
C.

a) Atomic models of heterostructures (HS) with S/S (left) and S/Se (right)
interface.
b) Photoluminescence spectra of individual monolayers and HSs.

World’s First Demonstration of Aluminum
Nitride-based Transistors

Manipulation of Optical Properties in Janus
WSSe/WS₂ Heterostructures

Aluminum nitride (AlN), an ultra-wide bandgap semiconductor,
is an attractive material for fabricating low-loss and highvoltage power devices due to its extremely large breakdown
field compared with those of conventional semiconductors. We
have operated AlN-based transistors for the first time in theworld; the key technologies are high-quality AlN crystal growthand good-contact electrode formation. Furthermore, goodtransistor performance is preserved even at a high temperatureof 500°C. Our achievement indicates that AlN-based transistors
are promising as next-generation power devices for meeting theever-increasing demand for operability at high temperatures.

2D transition metal dichalcogenides (TMDCs) with a TM (e.g.,W) layer between top and bottom layers containing different
chalcogen atoms (e.g., S in one and Se in the other) arecalled Janus TMDCs. We developed a growth technology forhigh-quality Janus TMDCs and fabricated Janus WSSe/WS₂
heterostructures with different stacking orders. Heterostructureswith S/S interfaces showed significant photoluminescence(PL) quenching in WS₂. In contrast, PL from WS₂ was enhanced
for those with S/Se interfaces. Janus TMDCs provide an
additional degree of freedom for manipulating the properties of
2D-material heterostructures.

M. Hiroki, Y. Taniyasu, and K. Kumakura, IEEE Electron Device Lett. 43, 350 (2022). Editors' Pick

(Left) Schematic (top) and cross-sectional electron microscope image (bottom) of
IL-CaCuO₂/Ca₂Fe₂O₅ superlattice.
(Right) Superconducting properties of IL-CaCuO₂/Ca₂Fe₂O₅ superlattice.

Design and Creation of New Cuprate
Superconductor Composed of Artificial
Superlattices
There have been only a few examples of novel cuprate
superconductors created by means of artificial superlattices.
Typically, such structural complexity arises from the factthat the superlattices are made of materials with different
crystal structures. Our custom-designed molecular beam
epitaxy apparatus, which is combined of a high-precision fluxrate control system and an elemental source sequencing, isa key for such new superlattice superconductors. Actually,
we have prepared high-quality superlattices composed of
CaCuO₂ and Ca₂Fe₂O₅ and found that this new superlattice is asuperconductor. This discovery holds promise for the creationof further new superconductors using our approach.

A. Ikeda, Y. Krockenberger, Y. Taniyasu, and H. Yamamoto, ACS Appl. Electron. Mater. 4, 2672 (2022).

U. Erkılıç, S. Wang, Y. Sekine, and Y. Taniyasu, Appl. Phys. Lett. 121, 113102 (2022).

pH dependence of budded baculoviruses fusion to artificial membranes.
(a) adsorption, (b) hemifusion, and (c) full fusion.

Incorporation of Membrane Proteins into Artificial
Lipid Bilayers by using Budded Baculovirus
Artificial bilayer lipid membranes (artificial membranes) havebeen used to evaluate functions of lipids and membraneproteins. However, efficient introduction of membraneproteins into artificial membranes had been a challenge. We
found that budded baculoviruses can be fused to an artificial
membrane formed on a silicon substrate efficiently under low
pH conditions. This finding enabled us to introduce membraneproteins into the artificial membrane.

A. Oshima, K. Nakanishi, N. Kasai, H. Nakashima, K. Tsumoto, and K. Sumitomo, Langmuir 38, 5464 (2022).

Multidisciplinary Materials Design and Science Laboratory

Drain current(A/mm)I (A/mm)

undoped AlN
SiC substrate

Vds = 20 V

-2

07

Advanced Applied Physical Science Laborator yGroups and Research Themes

Advanced Applied Physical Science
Laboratory
Overview
T he Advanced A pplied Physical Science L aboratory has
lau nched towa rds the creatio n of in novative informatio ncommunication technologies and future functional devices
that bring long-term value for the accelerating technologyd r i v e n s o c i e t y. L e a d i n g r e s e a r c h g r o u p s i n t h e f i e l d sof nanoelectronics, nanomechanics, nanophotonics,
spintronics, and quantum electronics are closelycollaborating for this exciting challenge. We will pioneer theforefront of the applied physical science field and discovernovel functionalities in solid-state quantum systems basedon our nanofabrication technology, advanced measurement
technology, and light-wave technology.

Nanodevice Research Group

Single-electron Devices for Ultimate Electronics
Highly accurate, highly sensitive, and low- power devices
based on single charge transfer and detection

Nanodevices with Novel Functions

Novel and high performance nanodevices based on silicon
and hybrid materials

Nanomechanics Research Group

Semiconductor Opto/electromechanics
Novel devices using mechanical functionality insemiconductor fine structures

Phonon Manipulation

P r o p a g a t i o n c o n t r o l o f a c o u s t i c w a ve s u s i n g a r t if i c i a l
structures

Quantum Optical Physics Research Group

Ma nip ulation of Ult rafast a n d Ult ra - st a ble L ase r
Field
Explore ultrafast physics and establish the standard opticalfrequency

Nano-scale Physics in Optically-active Materials

Characterize photons, excitons and spins in thesemiconductor nano-structures and rare-earth ions.

Photonic Nano-Structure Research Group
Integrated Nanophotonics Technologies

Ultra - compact and ultra -low power photonic devices andcircuits, novel photonic phenomena in nanostructures

Instrument to control optical dispersion andchirp for achieving ultrafast laser pulses inattosecond regime.

電流

100 nm

高周波信号あり0

10
20
時間 (s)

30

08

Achievements in 2022

英語版
w/o high-frequency signalecurrent

100 nm34

32

w/ high-frequency signal
01020Time (s)30(a) Scanning electron microscope of the single electron device.
(b) Response current by the AC signal.

Figure: Conceptual illustration of liquid probing with an optomechanical device (left).
and mechanical vibration spectra in liquid (right).

Single-electron Devices for Detecting Highfrequency Signals Beyond the RC Time ConstantHighly Sensitive Liquid Probing Using an
Optomechanical Device

Single electron devices that can control the motion of individual
electrons are promising for data processing utilizing single
electrons as bits of information. However, since the devices
are on the nanometer scale, their resistance is large and theiroperation speed is not fast. We succeeded in enabling a silicontransistor with a unique structure to respond signals fasterthan the speed determined by the resistance. This is due to thenonlinear electrical characteristics of the transistor, in whichleakage current is suppressed to the theoretical limit. Such a
fast-signal response would enable the transistor to function asa sensor detecting high-frequency signals.

In-liquid measurement technology using mechanical devices canbe used to detect fine particles and evaluate the viscoelasticity
of liquids. However, drastic improvements in the spatial resolution
and detection sensitivity of devices have been a challenge.
We have devised a new sensing method using optomechanicaldevices consisting of hair-sized glass wires that use light toprobe the mechanical vibration characteristics of liquids withultrahigh sensitivity. This technique has achieved picogram-levelmass detection sensitivity (equivalent to a single bacterium) andis capable of local characterizing phase-separated liquids. It is
expected to be used in a wide range of fields, including ultrasensitive chemical and biosensors and rheological applications.

K. Nishiguchi, A. Fujiwara, and K. Chida, 35th International Microprocesses and Nanotechnology
ConferenceHigh-Q(b)
Modal frequency (THz)

192.55

(a)

1
192.5

62

8 8

8 6
8 4
8 2

nm

)

68

s1 (

66

ift

65

64

sh

7 0
76 8

Ho
le s

le

hift
s

Ho

m)

9
9 6
9 4
9 2
8 0

2 (n

.45
192

67

Low-Q

.47
192

63

s1

EP

9
192.4

61

s2

Intensity (dB)

192.53(a) Our coupled photonic crystal nanocavities. The resonance frequency and radiation
loss of the lower cavity are varied by controlling the two hole shift parameters s1 and s2.
(b) Frequencies of the two eigenmodes dependent on s1 and s2. Blue symbols indicate
the system with a symmetry based on the contrast of loss. The red circle marks the EP.

Radiation-Induced Exceptional Point of
Coupled Photonic Crystal Nanocavities
Coupled cavities with a contrast of their on-site optical gain
(stimulated emission) and loss (absorption and radiation)
can have a peculiar degeneracy in their eigenmodes called
an exceptional point (EP). Optical systems with EPs exhibit
unconventional phenomena such as directional responses,
circularly polarized radiation, and enhanced emission. We
showed theoretically that we can obtain an EP in coupledsilicon photonic crystal nanocavities with contrasting radiation
losses. This design does not need any amplifying and absorbing
media or carrier excitation. Our work paves the way for theapplication of EPs in photonic devices without external controlof electrical or optical pumping of their active carriers.

K. Takata, N. Roberts, A. Shinya, and M. Notomi, Phys. Rev. A 105, 013523 (2022).

0(b)
Amplitude (dB)(a)

M. Asano, H. Yamaguchi, and H. Okamoto, Sci. Adv. 8, eabq2502 (2022).

-20

-40

-10
-20
-30

frep
2fceo

frep-2fceo

-40
-50
-60

-60
400

800

1200 1600 2000
Wavelength (nm)

2400

-70
0

100
200
Frequency (MHz)(a) Spectrum of supercontinuum light.
(b) Carrier-envelope offset signal by f-3f self-referencing interferometry.

Frequency Stabilization of an Optical
Frequency Comb with a Single SiN
WaveguideIn order to use the optical frequency comb outside thelaboratory, a compact and frequency-stabilized opticalfrequency comb light source is required. By designing thedispersion of the SiN waveguide and optimizing the width andlength of the waveguide, we succeeded in generating ultraw i d e b a n d s u p e r c o n t i n u u m l i g h t f r o m 400 t o 2500 n m a n dstabilizing the carrier-envelope offset frequency with f-3f selfreferencing interferometry. We believe that this method, whichenables frequency stabilization with a single optical element, isa promising compact optical frequency comb light source.

A. Ishizawa, K. Kawashima, R. Kou, X. Xu, T. Tsuchizawa, T. Aihara, K. Yoshida, T. Nishikawa, K. Hitachi,
G. Cong, N. Yamamoto, K. Yamada, and K. Oguri, Optics Express 30 (4) 5265 (2022).

Advanced Applied Physical Science Laboratory

Transistor

Response current (nA)

(b)

(a)

09

Quantum Science and Technology Laborator yGroups and Research Themes

Quantum Science and Technology
Laboratory
Overview
T h e Q u a nt u m S cie n c e a n d Te c h n o l o g y L a b o ra to r y willcontribute to the exploration of the quantum science field
and the development of new technologies for overcomingth e co nve ntio nal info rmatio n p ro cessing limits withq u a n t u m - e n a b l e d d evi c e s a n d s y s te m s . W it h q u a n t u minformatio n theor y a nd our experimental research inphotonic, semiconductor, and superconducting systems asa basis, we aim to achieve new technologies in the areasof quantum communication , quantum sensing , opticaloscillator-based computing, and quantum computing basedon superconducting circuits and topological phenomena.

Q ua ntum Optical State Cont rol Resea rch
Group
Photonic Quantum Communication

Control of quantum state of light and its application to novelcommunication systems

No n -vo n Ne u m a n n Com p u t at io n Usi n g Q u a n t u m
OpticsNew computers based on coupled optical oscillators

Theoretical Q ua ntum Physics Resea rch
Group
Theoretical Quantum Information Science

Proposal and systematic design of quantum computation,communication, network and metrology schemes includingarchitectures.

Superconducting Quantum Circuits Research
Group
Superconducting Quantum Circuits

Manipulating quantum states using superconducting
devices

Ultimate Quantum Measurement and Sensing

Highly sensitive measurement technologies using quantum
mechanical effects

Quantum Solid State Physics Group

Quantum Transport in Hetero- and Nano-structures
based on Semiconductor and 2D Materials
Unconventional charge and spin transport phenomena inquantum devices

Fast Coherent Carrier Dynamics in Electronic Devices
Information processing with coherent electron motion3

He/4 He dilution refrigerator used to carryout low-temperature (below 100 milli-kelvins)
experiments for superconducting andsemiconductor quantum devices.

10(conv)|hOverlap
Φ(T)|Ψ(T)icos( bounds)n Lnand |,
its lower
オーバーラップとその下限

Achievements in 2022

1

0.8
Q u a n t u m S c i e n c e a n d Te c h n o l o g y L a b o r a t o r y

P

0.6
0.4
0.2

Scalable Preparation and Measurementof d-dimensional Time-bin States in (d+1)
Mutually Unbiased Bases
A high-dimensional quantum key distribution (QKD) can
increase communication speeds by embedding multiple values
in a single photon. For a d-dimensional time-bin quantum
state, we devised a scalable implementation of (d+1) mutually
unbiased bases, with which we can improve the robustness
against communication errors. We observed acceptably low
symbol error rates for d-dimensional QKD. Our results constitutea basic element of an advanced secure communication system.

T. Ikuta, S. Akibue, Y. Yonezu, T. Honjo, H. Takesue, and K. Inoue, Phys. Rev. Research 4, L042007 (2022).

1000

10000

Numberof the slices
Trotter slices
Number oftheMTrotter

Overlap between true dynamics and simulated dynamics (red circles), our lower
bound (green squares), and conventional lower bound (blue triangles).

State-dependent Error Bound for Digital
Quantum Simulation of Driven Systems
Digital quantum simulation is a promising application ofquantum computers. In such a simulation, a time-evolution
operator is decomposed into simulatable quantum gate
operations. However, this decomposition causes some errors.
To evaluate these errors, we derived a lower bound for theoverlap between the true dynamics and the simulated dynamics.
Moreover, we also extended our formalism to digital quantum
simulation on NISQ computers.

T. Hatomura, Phys. Rev. A 105, L050601 (2022).

(b)
Current (a.u.)(a)Graphene
LT-GaAsZnO
VGate

Al 2O 3

1.0
0.8
0.6
0.4
0.2
0.0

A

-5

(c)

ZnO

Drain

SourcehBN/Graphene/hBN

0

5

10

15

20

25

Time (ps)1
4

Current (a.u.)(a) A part of the measurement device for a four-dimensional time-bin state.
(b) Conditional measurement probability distribution for the prepared and measured
states.

0100

2

220 GHz

0.1
4
2

0.01
4
2

0.001

3

4

5 6 7 8

0.1

2

3

4

5 6 7 81

2Frequency (THz)Spectrum of TLS defects (center). The types of defects can be identified bytheir slopes. (left) Schematic illustration of TLS defects with the charge-type
interaction. (right) Schematic illustration of TLS defects with the critical-currenttype interaction.

(a) Schematic of graphene photodetector. The inset shows the entire device
structure. (b) Waveform of photocurrent.
(c) Fourier spectrum of (b) showing 3 dB bandwidth of 220 GHz.

Detection of Two-level System Defects inSuperconducting Qubits

Ultrafast Optical-to-electrical Conversion inGraphene

A critical problem with superconducting quantum computersis the rapid loss of quantum information due to the interaction
between a qubit and its noisy environment. One of the main
noise sources associated with superconducting qubits is
atomic-scale two-level system (TLS) defects located insideoxide layers formed on the top of superconducting materials.
We developed a novel microwave technique that allows us
to identify the particular type of TLS defect. The approachcomplements methods for the characterization of other typesof noise in superconducting qubits and will enable further
improvements in the performance of superconducting quantum
processors.

Graphene photodetectors are promising next-generation
devices that have the potential to be highly sensitive andfast in their response to broadband light. However, until
now, their demonstrated operation speed at zero bias has
been hindered by factors such as the device structure andmeasurement equipment. By overcoming these limitations,
we achieved an operation speed of 220 GHz and clarified
the operating principle of graphene photodetectors. This
breakthrough provides useful design guidelines for maximizing
the performance of these devices.

L. V. Abdurakhimov, I. Mahboob, H. Toida, K. Kakuyanagi, Y. Matsuzaki, and S. Saito, PRX Quant. 3,040332 (2022).

K. Yoshioka, T. Wakamura, M. Hashisaka, K. Watanabe, T. Taniguchi, and N. Kumada, Nat. Photonics 16,
718 (2022).

11

Nanophotonics Center

Nanophotonics Center

Nanophotonics Center

Overview
T h e N a n o p h oto nic s C e nte r was esta blis h e d in A p ril
2 012 a n d i s c o m p o s e d o f s e v e r a l g r o u p s i n v o l v e din nanophotonics research at NT T Basic Research
L a b o rato ries a n d N T T D evic e Te c h n olog y L a b o rato ries .
We are conducting studies of photonic crystals to reduce
the footprint and energy consumption of various photonic
d evices , such as o ptical switches , o ptical memories ,modulators , lasers , and photo - detectors . We are also
studying various photonic nanostructures to greatly enhancelight-matter interactions, and exploiting photonic integrated
circuits and devices for on-chip signal processing.
Research Themes
Extreme enhancement of light-matter interactions by using photonic
crystals and plasmonics● Integrable nanophotonic devices with extremely small energy
consumption● Novel optical platforms using nanomaterials and nanophotonics● Nanophotonic computations with photonics-electronics convergence●

Research Center for Theoretical Quantum Physics

R e s e a rc h C e n t e r f o r T h e o re t i c a l Q u a n t u m P h y s i c s

Research Center for Theoretical Quantum Physics

Overview
The twentieth century saw the discovery of quantum mechanics, a setof principles that explains the nature of matter and light at the atomic
level. These counter-intuitive principles have not only dramaticallychanged our understanding of the reality of our physical world but
also enabled a technological revolution. They are responsible forthe digital age in which we live. Naturally arising questions are whatfurther we can learn from these principles and what technologicaladvances could be enabled. The Center for Theoretical Quantum
Physics established in July 2017 brings together diverse researchers(physicists, computer scientists, mathematicians and even chemists)
fro m a cross N T T to p u rsu e cut ting e dge resea rch in a hig hly
collaborative environment.
Research Themes
The foundation of quantum mechanics
Quantum matter
Quantum algorithms and complexity● Quantum communication, simulation and computation● Quantum metrology and sensing● Atomic, molecular and optical physics●●●

Bio-Medical Informatics Research Center

B i o - M e d i c a l I n f o r m a t i c s R e s e a rc h C e n t e r

Bio-Medical Informatics Research Center

Overview
The Bio - M edical Informatics Research Center (B M C) wasestablished in J uly, 2019 as a research organization in which
related N T T laboratories collaborate with the goal of creating
data - driven medicine using I CT and A I . T he B M C engages inbasic and applied research on AI analysis of medical and healthdata , genome informatio n a nd behavior informatio n , real-time
bio m o nito ring in d aily life , bio mim etic n a n o d evic es , a n d n ew
biocompatible materials. In addition, it promotes innovations inmedical and health fields in cooperation with partners at medical
institutes and Medical & Health Informatics Laboratories (M EILab), NTT Research Inc.
Research Themes
Personalized medicine by AI analysis of personal medical data (precision
medicine)●Cardiac modeling and rehabilitation activities supported by AI-telestethoscope and hitoe® ECG measurement●Lifestyle-related disease management based on noninvasive blood glucose
sensor and core body temperature sensor●Fabrication of implant materials and artificial neural networks thatcomplement biological functions●

12

Achievements in 2022

F. Tian, H. Sumikura, E. Kuramochi, M. Takiguchi, M. Ono, A. Shinya, and M. Notomi, Optica 9, 309 (2022).

(c)

(b)

Optomechanical (OM) cavity
PhotonCollision

We have demonstrated a novel optomechanical cavity quantum
electrodynamics (QED) system in which optical transition, opticalresonance, and mechanical resonance are strongly coupled. Our
device consists of copper-doped Si double nanobeam photonic
crystals, which function as a strongly-coupled hybrid resonator witha high-Q optical cavity and a high-Q mechanical cavity. When thesystem was excited by repetitive laser pulses, we demonstrated
dynamic modulation of the spontaneous emission rate inducedby the mechanical resonance tuning. This phenomenon meansthat we can dynamically control the cavity QED effect, in which
spontaneous emission is enhanced by optical resonance, via
mechanical oscillation, thereby paving the way to novel hybrid
quantum systems.

(a)

Pump

Dynamic Modulation of Spontaneous Emission
with Optomechanical Hybrid Cavity Quantum
Electrodynamics System(d)
OM modulated SE(a)Schematicdiagramofahybridizedoptomechanicalcavity-QEDsystem.
(b)Spectralillustrationofthedynamicsofthehybridsystem.
(c)Practicalconfigurationoftheoptomechanicalcavity(upper:opticalandmechanicalresonancem
odes;lower:SEMimage).
(d)Experimentalresultsofdynamicallyenhancedspontaneousemission.

Data processsing

Input layer

Quantum hidden layer

M-layerClassical processor

Quantum Reservoir(Quantum processor)

PCA Map

Today’s NISQ processors have allowed us to enter an era wheretasks can be performed that are hard to achieve on supercomputers.
However, the tasks that have been performed so far are quite
abstract and not so practical. Here, we introduce a resourceefficient quantum neural network model with a focus on therole of the feature space the quantum processors can give forclassification tasks. We show how complex scale-free networks
generated in a discrete-time crystal model can provide a feature
space with distinct quantum advantage. Importantly, our model does
not require optimization of the quantum processor to the particularclassification task.

EncorderQuantum Extreme Reservoir Computation

Output layer
PCA Map

0
9
Scale-free network(b)

Skin-Attachable Core Body Thermometer for
Visualization of the Circadian Rhythm
The temperature of internal organs located deep in the body (corebody temperature (CBT)) exhibits a 24-hour rhythm linked with
the internal clock of the body. Conducting an orderly life alignedwith this internal clock can reduce the risk of mental and physicalillness. However, the procedure for monitoring the temperature
can be stressful. We addressed this problem by developing a skinattachable CBT sensor that has a unique structure designed toreduce the effect of ambient convection and thereby reduce thenumber of errors. We verified the operation of the sensor throughnumerical calculations and in-vitro experimentation. Then we used
it in a visualization of the CBT behavior during sleep.

Y. Tanaka, D. Matsunaga, T. Tajima, and M. Seyama, IEEE Sensors Journal, 21, 16118 (2021).
D. Matsunaga, Y. Tanaka, T. Tajima, and M. Seyama, 44th Annual International Conference of the IEEE
Engineering in Medicine & Biology Society (EMBC), 1258 (2022).

独自の金属構造.

深部体温(℃)

貼り付け型
深部体温センサ(a)(c)

Skin attachable
CBT sensor.

(b) Unique metal structure.
Heat flux
and temperature sensor

ー貼り付け型深部体温センサ

時刻

皮膚温度と熱流束センサ

Core body temperature (℃)

A. Sakurai, M. P. Estarellas, W. J. Munro, and K. Nemoto, Phys. Rev. Applied 17, 064044 (2022).

Schematic illustration of the structure of the quantum extreme reservoir computer(a)(c)
utilizing both quantum (red) and classical(yellow) data processing. The quantum
reservoir is formed using a scale-free networks generated
in a discrete-time crystal.
ー鼓膜温度（医療機器）(a) Photograph of CBT sensor.
(b) Schematic of internal structure.
(d) Typical CBT behavior during sleep.

ーTympanic temperatureーProposed sensor

Time

13

The title of "NTT Fellow" is reserved for our most gifted scientist and engineers whose research and development activities
have brought them significant distinction both within NTT and internationally. Our "Fellows" are extremely highly regarded. Next
the title of "Senior Distinguished Researcher" is given to outstanding individuals who have established themselves as global
intellectual leaders of their own research areas. The "Distinguished Researcher" title is given to innovative researchers whose
impressive achievement has been recognized both within and outside NTT.
They all are responsible for leading innovative research and cutting-edge technical developments in research areas considered
important to NTT.
D e c e m b e r 31 , 2022

NTT Fellow

Shingo Tsukada

Hiroshi Yamaguchi

Medicine, Physiology, Biomedical
interface & data analysis

Quantum and Nano Device
ResearchResearch Subject

Research Subject

Biological Information Elucidation

Nano-mechanics in
Semiconductors

Using Advanced Medical Materials

Senior Distinguished Researcher

Masaya Notomi

Hideki Yamamoto

Koji Muraki

Research Subject

Photon Manipulation in Photonic
Nanostructures

Akira Fujiwara

Multidisciplinary Materials Design andScience Laboratory Executive Manager

Nanophotonics Center ProjectManager

Research Subject

Research Subject

Research Subject

Electron Correlation in
Semiconductor Nanostructures

Design and thin-film synthesis of novel
superconductors and magnetic materials withelucidation of the underlying physics

Ultimate Electronics Using
Semiconductor Nanostructures

William John Munro

Hiroki Takesue

Shiro Saito

Yoshitaka Taniyasu

Research Center for Theoretical
Quantum Physics Project Manager

Quantum Science and Technology
Laboratory Executive Manager

Quantum Optical Physics ResearchGroup Leader

Thin-Film Materials Research Group Leader
Low-Dimensional Nanomaterials Research Group Leader

Research Subject

Research Subject

Research Subject

Research Subject

The Design of Quantum Technologies

Quantum Communication
Experiments in
Telecommunication Band
Coherent Ising Machine

Quantum information technologies
based on superconducting
quantum circuits

Research on functional materials
for green innovation

Distinguished Researcher

Norio Kumada
Katsuhiko Nishiguchi

Haruki Sanada
Imran Mahboob

Kengo Nozaki
Koji Azuma

Takahiro Inagaki
Hajime Okamoto

Gento Yamahata
Masayuki Hashisaka

14

Publication List

The total number of NTT Basic Research Laboratories papers published ininternational journals in 2022 is 64 with an average impact factor of 5.905.
The 2021 impact factor of those individual journals are shown in ( ).

PHYSICAL REVIEW B (3.908)

8
5

PHYSICAL REVIEW A (2.971)

5

JAPANESE JOURNAL OF APPLIED PHYSICS (1.491)
4

PHYSICAL REVIEW RESEARCH (＊)
NATURE COMMUNICATIONS (17.694)

3

PHYSICAL REVIEW APPLIED (4.931)

3
3

APPLIED PHYSICS LETTERS (3.971)
SCIENCE ADVANCES (14.957)

2

COMMUNICATIONS PHYSICS (6.497)

2

PHYSICAL REVIEW MATERIALS (3.98)

2

OPTICS EXPRESS (3.833)

2

APPLIED PHYSICS EXPRESS (2.819)

2
2

AIP ADVANCES (1.697)
NATURE PHOTONICS (39.728)

1

BIOSENSORS & BIOELECTRONICS (12.545)

1

NPJ COMPUTATIONAL MATERIALS (12.256)

1

OPTICA (10.644)

1

PHYSICAL REVIEW LETTERS (9.185)

1

NANOPHOTONICS (7.923)

1

PRX QUANTUM (7.514)

1

NPJ QUANTUM MATERIALS (6.856)

1IEEE ELECTRON DEVICE LETTERS (4.816)

1

LANGMUIR (4.331)

1

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN (1.933)

1
1

2

3

4

5

6

7

Number of Presentations

Number of Patents

118

43

（37 Invited talks）

8

List of Award Winners
The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology: Awards
for Science and Technology in Research Category
Telecommunication-band Quantum Optics and its Application to Information Processing

Hiroki Takesue

The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology of Japan,
The Young Scientists' Prize
Theoretical study of quantum repeaters towards a quantum internet

Koji Azuma

The 3rd Fumiko Yonezawa Memorial Prize of the Physical Society of Japan

Research on Quantum Transport and Control of Spin-orbit Interaction in Novel Semiconductor Materials

Keiko Takase

14th Conference on Laser and Electro-Optics Pacific Rim (CLEO Pacific Rim 2022) Best Paper Award
Erbium-doped Rare-Earth Oxide Thin Film Waveguides for Integrated Quantum Photonic Devices

Xuejun Xu, Masaya Hiraishi, Tomohiro Inaba, Tai Tsuchizawa, Atsushi Ishizawa, Haruki Sanada, Takehiko Tawara, Jevon Longdell, Katsuya Oguri,and Hideki Gotoh

18th International Workshop on Nanomechanical Sensing (NMC2022) Best Oral Presentation
An optomechanical prober in liquid with twin microbottle resonators

20th JSAP Photo & Illustration Contest, Excellent Award
Nano-size pencil?

Motoki Asano

Masato Takiguchi, Sylvain Sergent, Masaya Notomi, Stéphane Vézian, Benjamin Damilano