01

Message from the Director

We at NTT Basic Research Laboratories (BRL) are
extremely grateful for your interest and support withrespect to our research activities.
BRL’s mission is to promote progress in science andinnovations in leading-edge technology to advance
NTT's business. To achieve this mission, researchers
in various fields, including physics, chemistry, biology,
mathematics, electronics, informatics, and medicine,
conduct basic research on materials science, physicalscience, and optical science.
Our management principle is based on an "open door"
policy. For example, we are collaborating with many
universities and research institutes all over the world
as well as other NTT laboratories. We also organizes e v e r a l w o r k s h o p s a n d I S N T T, a n i n t e r n a t i o n a l
c o n f e r e n c e h e l d a t t h e A t s u g i R&D C e n t e r, t odisseminate our research output and hear the opinionsof the attendees. In addition, we hold the NTT-BRL
School, which is dedicated to the development of young
researchers around the world. To this school, we invite
distinguished researchers from around the world aslecturers to give young researchers, including thoseat NTT, the opportunity to learn from the foremost
authorities and share ideas with them.
Through these activities, we will continue to succeed
in promoting advances in science and innovations inleading-edge technology for NTT's business. Your
continued support will be greatly appreciated.

Front image:

Perovskite oxides
Complex oxides, which include
two or more cations in a unit
cell, especially those with theperovskite-related structures offer
a rich variety of functionalitiess u c h a s s u p e r c o n d u c t i v i t y,magnetism, and dielectricity.
They have been extensively
investigated from both scientificand technological viewpoints.
Researchers of NTT Basic
Re se a rch La b o rator ies havesucceeded in preparing theworld’
s best-quality thin filmsof such materials, including
trailblazing superconductors
and magnetic materials beyond
conventional concepts. Theyuse a unique oxide thin-film
growth technique that they havedeveloped over many years, withwhich atoms can be supplied ad
arbitrium in vacuum.

Activity Report

Advisor y Board
The NTT BRL Advisory Board, which
was first convened in 2001, held its
10th meeting on January 30 - 31,
2019. The aim of the Advisory Board
is to provide an objective evaluationof our research plans and activities
to enable us to employ strategic
management in a timely manner. At
this meeting, the BRL researchers
had a lunch and a poster session
with the board members, where
they had chances to present theirresearches to the board members ina casual atmosphere.

Director of NTT Basic Research Laboratories

02

Activity Report

N T T- B R L S c h o o l
The NTT-BRL School is held to foster the development of young
researchers and promote the international visibility of NTT.
In 2019, on the subject“Quantum Hybrid System”, we hadlectures by Prof. Göran Johansson and Prof. Per Delsing (bothfrom Chalmers University of Technology) and by Dr. Kouichi
Semba (National Institute of Communications Technology).
The program also included laboratory tours and a poster
session.

ISNTTInternational School and Symposium on Nanoscale Transport and phoTonics

The international school and symposium ISNTT, bienniallyheld in NTT-BRL, brings together leading scientists,
researchers, and graduate students to share their latest
research accomplishments and discoveries related to thephysics and technology of nanoscale structures.
ISNTT encourages frank and open technical discussions on
recent breakthroughs and advances in related research.
In 2019, we had 135 oral/poster presentations, including
keynote talks by Prof. Klaus von Klitzing (Max Planck
Institute) and Prof. Yasunobu Nakamura (University ofTokyo/Riken), and 19 invited talks.

International Symposium CNC
Coherent Network Computing

The International Symposium on Coherent Network
C o m p u t i n g ( C N C ) w a s h e l d f r o m M a r c h 18 t o
20 , 2019 , c o - s p o n s o r e d b y t h e J a p a n S c i e n c e
and Technology Agency (JST) and NTT Basic
Research Laboratories. A total of 138 researchers
attended and discussed various topics on network
computing based on various physical systems
and algorithms, such as coherent Ising machines,
quantum annealing, and combinatorial optimization
problems.

03

Organization

NTT Basic Research Laboratories

Director

Hideki Gotoh

Research Planning Section

Materials Science Laboratory

Physical Science Laboratory

Optical Science Laboratory

Executive Manager

Executive Manager

Executive Manager

Executive Manager

Kazuhide Kumakura

Hideki Yamamoto

P5

Akira Fujiwara

P7●Thin-Film Materials●Nanodevices Research

Research Group●Low- Dimensional
Nanomaterials Research
Group●Molecular and Bio Science
Research GroupGroup●Nanomechanics ResearchGroup●Superconducting Quantum
Circuit Research Group●Quantum Solid State
Physics Research GroupThe population data of NTT-BRL members●Researchers (Foreign Researchers)…９９（１２）●Research Associate/Specialist…１０●Joint Researcher…１
１●International Interns…２１＊●Domestic Interns…２
４＊●Invited professor…２＊●Guest Researchers…４＊

＊…Jan. to Dec. 2019 total

Hideki Gotoh

P9●Quantum Optical State

Control Research Group●Theoretical Quantum

Physics Research Group●Quantum Optical Physics

Research Group●Photonic Nano-Structure

Research Group04
As of Dec. 31, 2019

Advisor y Board

Affiliation is as of Jan. 30 , 2019

Forschungszentrum Jülich, Germany

Prof. Andreas Offenhäusser
University of Twente, The Netherlands

Prof. Dave H.A. Blank

Chalmers University of Technology, Sweden

Prof. Per Delsing

Laboratoire Kastler Brossel, France

Prof. Elisabeth Giacobino
CEA Saclay, France

Prof. Christian Glattli
Max-Planck-Institut für Festkörperforschung, Germany

Prof. Klaus von Klitzing

10th Advisory Board Meeting (January 30, 2019)

University of Illinois at Urbana-Champaign, U.S.A.

Prof. Sir Anthony J. Leggett

The University of Texas at Austin, U.S.A.

Prof. Allan H. MacDonald
Imperial College London, U.K.

Prof. Sir Peter Knight

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
Kwansei Gakuin University

Prof. Hiroki Hibino
Medical & Health Informatics Laboratories (MEI Lab),NTT Research, Inc.

Prof. Hitonobu Tomoike
Physics & Informatics Laboratories (PHI Lab),NTT Research, Inc.

Prof. Yoshihisa Yamamoto

05

Materials Science Laborator yGroup Introduction

Materials Science
Laboratory
Overview
The aim of the Materials Science Laboratory is to contributeto progress in materials science a n d to revolutio nize
information communication technology by creating novel
materials a n d fu nctio ns through materials d esign a n darrangement control at the atomic and molecular levels .
T h e re s e a rc h g ro u p s t h at c o n stit u te t his la b o rato r y a reinvestigating a wide range of materials including t ypical
semiconductors such as GaAs and GaN, two -dimensional
materials such as gra phene, oxide su perconductors a ndmagnetic materials , conductive polymers , and biologicals of t m a te ria ls . We a re c o n d u ctin g in n ova tive m a te ria ls
research based on advanced thin-film growth technologies
and high - precision and high - resolution measurements ofstructures and properties along with theoretical studies aswell as Materials 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 creation/conversion
devices, and novel multifunctional (optical, electric, andspintronic) 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 Soft Materials

Development and application of soft material composites formeasurement of deep biological information

Interface Interaction
Creation of biodevices and soft robots
by co ntrolling interactio ns at cell/cell a n d cell/n o n - cell
substance interfaces

Biosensing

O n - chip biosensing devices for biomolecular analysis at
molecular scale

06

Achievements in 2019English	S

D
GradedAlGaN layer

G
AlN:Si (500 nm)
AlN:SiHighest Curie temperaturein all insulators and oxides

AlN MESFET with graded AlGaN contact layer.

I-V characteristics of AlN MESFET

: Sr

[001]
-4

w/ graded AlGaN
[100]

-8

:O

w/o graded AlGaN

10
10
10

e

-10

0.2

0.4

0.6

0.8

[001]

1 nm
0

-200

0

Sr 3OsO 6

-12

0.0

10

f

⨀ [110]

200
400
600
Temperature (°C)
(K)

800

(-11)

[110]

-6

10

20

(-22)

: Os

(02)
(01)

[010]

[110]

30

(0-1)
(0-2)

Current (A/mm)

10[100] c40

Materials Science Laboratory
(2-2)
(1-1)

b

a

S.I.-SiC sub.

Magnetization (emu/cc)

un-AlN
un-AlN(800 nm)Sr 3OsO 6

d

g

1.0

Voltage (V)Ohmic contact characteristics for n-AlN with and without graded AlGaN(Left) Crystal structure of Sr₃OsO₆. (Right) Magnetization vs. temperature curve. (Inset
in right) Electron microscopy image of Sr₃OsO₆.

[001]

Ohmic Contact to n-type AlN Using Graded-AlGaN
Contact Layers and Operation of AlN MESFETs
The ultrawide bandgap semiconductor AlN has a breakdown
electric field about 40 times larger than Si’s and about fourtimes larger than GaN and SiC’s, which makes it attractive forhigh-voltage power applications. However, the large barrierheight between AlN and metals makes it difficult to form ohmic
contacts. We achieved good ohmic contacts to n-type AlN by
forming a compositionally graded-AlGaN contact layer in which
negative polarization charge density is controlled. As a result,
we demonstrated the operation of n-type AlN-MESFETs.

M. Hiroki and K. Kumakura, Appl. Phys. Lett. 115, 192104 (2019).

⨀ [100]Creation of Novel Ferromagnetic Insulator Sr₃OsO₆
W e s y n t h e s i z e d S r₃ O s O₆ , a n o v e l i n s u l a t o r t h a t e x h i b i t s
ferromagnetism above 780 °C,which surpasses the Curie
SrTiO
50 nm
5 nm
temperature record
among insulatorsfor 3the firsttime in 88
years. Unlike most conventional magnetic materials, Sr₃OsO₆ isfree from Fe (iron) and Co (cobalt) and hence paves a new way
to the exploration and development of other novel magnetic
materials. This brand-new material is promising for highperformance magnetic devices that can be stably operated athigh temperatures (room temperature to 250 °C).

Y. K. Wakabayashi, Y. Krockenberger, N. Tsujimoto, T. Boykin, S. Tsuneyuki, Y. Taniyasu,
and H. Yamamoto, Nat. Commun. 10, 535 (2019).

Glass substrate
Adhesive region

Partial adhesion

Patterning of adhesive region

1	
  mm	

1	
  mm	

Fabrication of hydrogel film
2D-flat

Controlled buckling

Swelling-induced 3D architecture
Fluorescence image(side view)

Fluorescence image(top view)

400	
  μm	
Cooling（Swelling）

400	
  μm	

Heating（Deswelling）

3D-hollow

Schematic of CVD growth of h-BN on Cu. Single-orientation and multi-orientationh-BN grown on inclined Cu (101) and other facets, respectively.

Single-orientation Growth of 2D Hexagonal Boron
NitrideControlling the crystallographic orientation of 2D materials
is essential for tailoring their properties and engineering 2D
functional devices. Here we demonstrated that hexagonal boron
nitride (h-BN), an ideal 2D dielectric, has a single orientation
on inclined Cu (1 0 1) surfaces, where the Cu planes aretilted from the (1 0 1) facet around specific in-plane axes. The
single-orientation h-BN is free of wrinkles and exhibits electricperformance with excellent homogeneity on a large scale.
These findings will pave the way for the integration of 2D
functional devices on large-scale substrates.

S. Wang, A. E. Dearle, M. Maruyama, Y. Ogawa, S. Okada, H. Hibino, and Y. Taniyasu, Adv. Mater. 31,
1900880 (2019).

（upper）3D	
  architecture	
  forma4on	
  based	  on	
  swelling	
  pressure	
  of	
  hydrogel	
  ﬁlm.	
  （lower	
  le?）Buckling	
  at	
  an	
  arbitrary	
  posi4on.	
  （lower	  right）Reversible	
  switching	
  of	
  3D	
  hydrogel	  architecture	
  (2D	
  ﬂat-­‐	  3D	
  hollow)	
  u4lizing	
  temperature	
  responsive	
  gels.	

3D Hydrogel Architecture Induced by Swelling
Hydrogels, which consist of a polymer network and water,show characteristic properties such as biocompatibility andvolume changeability due to swelling. In this research, weestablished a method for creating 3D hydrogel architectures at
an arbitrary position on hydrogel/glass substrate composites
to which the desired interface is adhered. By introducing astimuli-responsive unit into the hydrogel, we successfully
demonstrated reversible switching between 2D flat and 3D
hollow architectures. This dynamic tuning of a 3D hydrogelarchitecture has great potential for 3D cell culture substrates
and soft actuators.

R. Takahashi, H. Miyazako, A. Tanaka, and Y. Ueno, ACS Appl. Mater. Interfaces 11, 28267 (2019).

SrTiO 31 nm

07

Physical Science Laborator yGroup Introduction

Physical Science
Laboratory
Overview
The Physical Science Laboratory aims to develops e mic o n d u cto r- a n d s u p e rc o n d u cto r- b a s e d d evic e s a n dhybrid-type devices, which will have a revolutionary impact
on the ICT society of the future. We are using high-quality
crystal growth and nanofabrication techniques to explore
novel properties that could lead to nanodevices for ultimate
electronics and novel information processing applications
based on new degrees of freedom such as single electrons,mechanical oscillations, quantum coherent states, electron
correlation, and spins.

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

Superconducting Quantum Circuit 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.

08

Achievements in 2019

f

VDC1

EnergyTunneling
Ultrafast
coherent oscillations

ElectronExit

f = 2 GHz, Temperature = 4.2 K
SiliconNonlinear
Measurement
Pseudo-angular momentum

Random motion in oscillators

50 μm

Silicon nitride resonator0.25 Terahertz

y2 (a.u.)𝑦𝑦2 (a.u.)

Noise squeezing

Gate electrodes
Image of the device and operation.

(Top) Electron potential diagram of the singleelectron source.
(Bottom) Current oscillations originating from thecoherent oscillations.

Without filtering𝑥𝑥1 (a.u.)With filtering𝑥𝑥1 (a.u.)

Measurements of Ultrafast Coherent Oscillations in
a Silicon Single-electron Source

Mechanical Noise Squeezing Via Nonlinear
Measurement

In a single-electron source that can periodically emit electrons
one by one, we have succeeded in time-resolved detectionof ultrafast quantum-mechanical coherent oscillations inthe sub-terahertz regime, which are impossible to detect
using existing measurement techniques. We detect them bytemporally changing the energy of an oscillating electron andutilizing tunneling, which is allowed in a narrow energy band,through a resonant level. This is a new technique aiming for theobservation of ultrafast quantum phenomena and could lead toa readout of ultrafast quantum bits.

An important issue in sensing applications with a mechanicalresonator is how to reduce mechanical noises to increase
sensitivity. We proposed a scheme for noise squeezing anddemonstrated it with a silicon-nitride resonator. So far, an
external driving force has been required for noise squeezing.
We succeeded in noise squeezing by directly observing a
pseudo-angular momentum between mechanical modes via
an optical nonlinear measurement and by filtering out its
polarity. This result can be extended to novel technologies forcontrolling mechanical systems without an external driving
field.

Inp

lan

em

ag

en

ne

se

mb

x
Flu bit
qu
le

tic
fie
ld

e
lin
MW on
ic
Sil

Spin excitation

Magnetic flux (mΦ0)

Sp
in

M. Asano, R. Ohta, T. Aihara, T. Tsuchizawa, H. Okamoto, and H. Yamaguchi, Phys. Rev. A 100, 053801(2019).

Switching probability (%)

G. Yamahata, S. Ryu, N. Johnson, H.-S. Sim, A. Fujiwara, and M. Kataoka,Nat. Nanotechnol. 14, 1019 (2019).

Spin excitation frequency (GHz)(Left) Electron spin resonance spectrometer using a superconducting flux qubit.
(Right) Electron spin resonance spectrum of nitrogen-vacancy centers in diamond.

Electron Spin Resonance Spectroscopy Using a
Superconducting Flux Qubit

Clarification of Equilibration Process of Quantum
Hall Edge Current

We developed an electron spin resonance spectrometer using
a superconducting flux qubit with sensing volume of 50 fL
a n d s e n s i t i v i t y o f 400 s p i n s / √H z . T h i s s p e c t r o m e t e r c a n
sweep the magnetic field and microwave frequency for the
spectroscopy, making it possible to refine material parameters.
The high spatial resolution also enables us to obtain the spatial
distribution of electron spins in materials.

In the quantum Hall effect, which is used as an electricalresistance standard, a unidirectional edge current withoutbackscattering flows along the edge of a sample due to thecyclotron motion under the influence of a repulsive potential at
the edge. We investigated the quantum Hall effect in a sample
with an attractive edge potential and detected counterflowingedge current. Furthermore, we have clarified the equilibration
process in which the counterflowing edge current decays as the
distance increases. Clarification of the edge state is important
for realizing fault-tolerant quantum computing based on thequantum Hall effect.

H. Toida, Y. Matsuzaki, K. Kakuyanagi, X. Zhu, W. J. Munro, H. Yamaguchi, and S. Saito,
Commun. Phys. 2, 33 (2019).

T. Akiho, H. Irie, K. Onomitsu, and K. Muraki, Phys. Rev. B 99, 121303(R) (2019).

Physical Science Laboratory

Resonantlevel
Entrance

Current measurements

VDC2

09

Optical Science Laborator yGroup Introduction

Optical Science
Laboratory
Overview
The Optical Science Laboratory is pursuing the developmentof c o re te c h n ologies th at will le a d to in n ovatio ns in
optical communication and optical signal processing andto f u n d a m e nt al s cie ntific p ro g re s s . C e nt ral t h e m e s a requantum communication, physical computing with opticaltechniques, ultra-short light-matter physics pulse light, theoptical frequency standard, and optical and spin properties
in nanostructures.

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.

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.

10

Achievements in 2019

英語版
High edge density graph(edge density = 50%)

Low edge density graph(d: number of edges per vertex)

Coherent
Ising machine (CIM)

Optical Science Laboratory

Success probability

CIM(d=3) QA(d=3)

CIM(50%)Calculation
time of QA
Quantum
annealing
Machine (QA)

QA

Problem size

Experimental setup

Experimental Investigation of Performance
Differences Between Coherent Ising Machines anda Quantum Annealer
We have developed a coherent Ising machine based on a
network of degenerated optical parametric oscillators tosolve combinatorial optimization problems. We performed abenchmark study in which we compared the CIM with a quantum
annealing machine based on a network of superconducting
qubits. An evaluation of the success probability of the groundstate search problem for various graph instances confirmedthat our CIM can solve high-edge-density graphs with successprobabilities higher than those of the quantum annealing
machine.

R. Hamerly, T. Inagaki, P. L. McMahon, D. Venturelli, A. Marandi, T. Onodera, E. Ng, C. Langrock, K. Inaba, T. Honjo,
K. Enbutsu, T. Umeki, R. Kasahara, S. Utsunomiya, S. Kako, K. Kawarabayashi, R. L. Byer, M. M. Fejer, H. Mabuchi,
D. Englund, E. Rieffel, H. Takesue, and Y. Yamamoto, Sci. Adv. 5, eaau0823 (2019).

First Proof-of-principle Experiment of All-photonic
Quantum Repeaters
A quantum internet, enabled by quantum repeaters, is theHoly Grail of information-processing networks. It will havecapabilities far exceeding those of the current Internet,
such as quantum cryptography and quantum computation. In
collaboration with Osaka University, the University of Toyama,
and the University of Toronto, we have successfully conducteda proof-of-principle experiment for all-photonic quantum
repeaters. This opens a path to an energy-efficient high-speed
global‘all-optical’quantum internet.

Y. Hasegawa, R. Ikuta, N. Matsuda, K. Tamaki, H.-K. Lo, T. Yamamoto, K. Azuma, and N. Imoto,Nat. Commun. 10, 378 (2019).

EnglishOptical output(a)Plasmonic
waveguide

Plasmonic mode converter(b)

Au

GrapheneSi

1 Pm

Optical input
Electron microscopy images and lasing spectra(a) Schematic of the graphene-loaded plasmonic waveguide.
(b) Scanning electron microscope image of the plasmonic mode converter.

ナノワイヤの電子顕微鏡写真・発光スペクトル
Telecom-band
Nanowire Lasers

Ultrafast and Energy-efficient All-optical Switching

We have established a technology in which a bottom-up selfcatalysed vapor-liquid-solid method is used to grow InP/
InAs heterostructure semiconductor nanowires. When the thethickness of an InAs quantum disk is precisely modulated, thehigh-quality crystalline nanowire structure achieves lasing atroom temperature in the whole telecom-band range of 1300–
1600 nm. This technology is expected to produce a seamlessconnection between the direct formation of a coherent lightsource, which has been the biggest obstacle to developing
optical-electronic integrated circuits, and an optical fiber
communications network.

Previously reported all-optical switches would have difficulty
operating at an ultrahigh speed with low energy consumption.
We have demonstrated an ultrafast all-optical switching
operation with the lowest energy consumption (35 fJ/bit) everreported for all-optical switching at less than one picosecond.
The current achievement combines a plasmonic waveguidewith a core size of 30 nm × 20 nm with graphene, which has anultrafast nonlinear optical response. Such ultrahigh switching
speed cannot be achieved by electrical control. It is expectedthat this switch will be used in future photonic integrated
circuits for ultrafast information processing.

G. Zhang, M. Takiguchi, K. Tateno, T. Tawara, M. Notomi, and H. Gotoh, Sci. Adv. 5, eaat8896 (2019).

M. Ono, M.Hata, M. Tsunekawa, K. Nozaki, H. Sumikura, H. Chiba, and M. Notomi, Nat. Photonics 14, 37(2020).

2

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.
Extreme enhancement of light-matter interactions by using photonic
crystals and plasmonics
Integrable nanophotonic devices with extremely small energy
consumption● Nano-imprint, SPM lithography and manipulation● Integration of various high-performance devices on a silicon platform●●

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 can we learn from these principles and what technologicaladvances could be enabled. The newly formed Center for Theoretical
Quantum Physics established in July 2017 brings together diverse
researchers (physicists, computer scientists, mathematicians andeven chemists) from across NTT to pursue cutting edge research in ahighly collaborative environment.
The foundation of quantum mechanics
Quantum matter (hybrid quantum systems, strongly correlated systems,
condensed matter and superconducting systems)● 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
five NTT laboratories collaborate with the goal of creating datadriven medicine using ICT. The BMC engages in basic and appliedresea rch o n A I a nalyses of medical a n d health data , genome
informatio n a n d b ehavior informatio n , real-time biomo nitoringin daily life, biomimetic na no d evices , a n d new biocom patible
materials . I n addition , it promotes innovations in medical andhealth fields in cooperation with partners at medical institutes
and Medical & Health Informatics Laboratories (MEI Lab), NT T
Research, Inc.
Personalized medicine by AI analysis of personal medical data (precision
medicine)●Long-term Holter ECG measurement and rehabilitation activity supported
by hitoe●Lifestyle-related disease management based on noninvasive blood glucose
sensing, core body temperature measurement, and AI risk analysis●Fabrication of implant materials and artificial neural networks thatcomplement biological functions●

12

Achievements in 2019

Optical Transistor
We used photonic-crystal nanostructures to fabricate an ultrasmallenergy-saving photodetector (O-E converter) and optical modulator(E-O converter). By closely integrating these two converters, we
succeeded in operating an optical transistor (O-E-O converter),which can transfer optical signal data to another light with signal
gain. The capacitance of the device is remarkably suppressed down
to only 2 fF, which results in an operating energy that is two-ordersof magnitude smaller than those for existing technologies. Sucha nanophotonic device will serve as a fundamental component for
high-speed opto-electronic signal processing chip.

InGaAs-embedded
nano-photodetector

InGaAsP-embedded
nanocavity modulator

Outputoptical signal

10 Gbit/s
n

p

p
Input
optical signal

Optical signal gainn
Au

Photonic
crystal3

Max. 2.3 ± 0.3

2

Gain
1

0
1530.0 1530.5 1531.0 1531.5

Load resistor 24 kW

Continuous light

Wavelength for modulator [nm]K. Nozaki, S. Matsuo, T. Fujii, K. Takeda, A. Shinya, E. Kuramochi, and M. Notomi, Nat. Photonics 13, 454(2019).

Q u a n t u m K e y D i s t r i b u t i o n E n a b l i n g 500－k m
Cryptographic Communication and its Security0

log 10[Secret key rate (per pulse)]

Quantum key distribution (QKD) presents secure communication
against arbitrary eavesdropping, including attacks based on
quantum computers. Recently, twin-field QKD was proposed as ascheme to surpass the private capacity of a point-to-point（Pt2Pt）
optical fiber link by using a repeater node between communicators.
However, its security was merely a conjecture. In collaboration
with the University of Vigo and the University of Toronto, we haveproposed a simpler twin-field QKD scheme and proved its security.
Our scheme exceeds the point-to-point private capacity, opening up
the possibility of quantum cryptography within a radius of 500 km.

-2-4

Our protocol(with a dark count rate of 10‐8）-6

Pt2Pt private capacity

-8

-10
0

20

40

60

80

Loss between communicators [dB]

M. Curty, K. Azuma, and H.-K. Lo, npj Quantum Inform. 5, 64 (2019).

Reconstitution of a Neural Network Using a Thin-filmbased 3D Template
We demonstrated that graphene, a carbon-based nanomaterial,
spontaneously assembles into a three-dimensional structure whentransferred onto a polymeric thin film. The assembled 3D structure
was used as a cell scaffold on which neurons were successfully
cultured and reconstituted into functional neuronal tissue. The
reconstituted neuronal tissues were found to exhibit cell-cellinteractions by forming a network in which they were connected
to external neurons. Owing to the excellent conductivity ofgraphene, the technology developed in this study can be applied
to not only new tools for cell biology and tissue engineering but tobiocompatible and implantable bioelectrodes as well.

T. F. Teshima, C. S. Henderson, M. Takamura, Y. Ogawa, S. Wang , Y. Kashimura, S. Sasaki,
T. Goto, H. Nakashima, and Y. Ueno, Nano Lett. 19, 461 (2019).
K. Sakai, T. F. Teshima, H. Nakashima, and Y. Ueno, Nanoscale 11, 13249 (2019).

100

120

13

NTT Fellow

The title of "NTT Fellow" is reserved for our most gifted scientist and engineers whose
research and development activities have brought them significant distinction bothwithin NTT and internationally. Our "Fellows" are extremely highly regarded. Next the

Medicine, Physiology, Biomedical interface & data analysis

title of "Senior Distinguished Researcher" is given to outstanding individuals who haveestablished themselves as global intellectual leaders of their own research areas. The

Shingo Tsukada"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 technicaldevelopments in research areas considered important to NTT.
D e c e m b e r 31 , 2019

Senior Distinguished Researcher

Nanophotonics Center Project Manager

Quantum and Nano Device Research

Quantum Solid State Physics Research Group Leader

Masaya Notomi

Hiroshi Yamaguchi

Koji Muraki

Research Subject

Research Subject

Research Subject

Photon Manipulation in Photonic

Nano-mechanics inElectron Correlation in

Nanostructures

Semiconductors

Semiconductor Nanostructures

Physical Science Laboratory Executive Manager

Research Center for Theoretical Quantum Physics Project Manager

Quantum Optical State Control Research Group Leader

Akira Fujiwara

William John Munro

Hiroki Takesue

Research Subject

Research Subject

Research Subject

Ultimate Electronics Using

The Design of Quantum Technologies

Quantum Communication

Research Subject

Biological Information Elucidation
Using Advanced Medical Materials

Semiconductor Nanostructures

Experiments in Telecommunication
Band
Coherent Ising Machine

Distinguished
Researcher

Norio Kumada
Katsuhiko Nishiguchi

Shiro Saito
Haruki Sanada
Imran Mahboob Koji Azuma

Kengo Nozaki Hiroki Mashiko
Yuko Ueno
Takahiro Inagaki

14

Publication List（）
…The average IF2018 for all research papers from NTT Basic Research Laboratories is 5.689＊…IF has not counted because the journal started 2018.
The number of papers published in international journals in 2019 is 103.

PHYSICAL REVIEW A (2.907)

11
9

PHYSICAL REVIEW B (3.736)
8

JAPANESE JOURNAL OF APPLIED PHYSICS (1.471)
7

APPLIED PHYSICS LETTERS (3.521)
6

OPTICS EXPRESS (3.561)
4

NANO LETTERS (12.279)

4

APPLIED PHYSICS EXPRESS (2.772)
ACS PHOTONICS (7.143)

3

PHYSICAL REVIEW APPLIED (4.532)

3
3

NEW JOURNAL OF PHYSICS (3.783)
NATURE PHOTONICS (31.583)

2

NATURE PHYSICS (20.113)

2

SCIENCE ADVANCES (12.804)

2

NATURE COMMUNICATIONS (11.878)

2

PHYSICAL REVIEW LETTERS (9.227)

2

NPJ QUANTUM INFORMATION (8.27)

2
2

JOURNAL OF APPLIED PHYSICS (2.328)
NATURE NANOTECHNOLOGY (33.407)

1

ADVANCED MATERIALS (25.809)

1

NANOSCALE (6.97)

1

COMMUNICATIONS PHYSICS (＊)

1

SCIENTIFIC REPORTS (4.011)

1
1

2

3

4

5

6

4

8

9

10

Number of Presentations

Number of Patents

222

77

（54 Invited talks）

List of Award Winners
JSPS PRIZE

Research on Wide Bandgap Semiconductor Ultraviolet Light-Emitting Devices

Yoshitaka Taniyasu

The Young Scientists' Prize, the Commendation for Science and Technology by the Minister of Education, Culture, Sports,
Science and Technology
Extremely-power-saving optical devices based on semiconductor photonic crystal

Kengo Nozaki

IEICE Technical Committee on Reconfigurable Systems

Design and implementation of FPGA measurement feedback system inCoherent Ising Machine

Achievement award in the laser society of Japan

Precision frequency conversion using an electo-optics-modulation comb

Creation of molecular recognition functional materials and its application to micro analysis

IOP Publishing Outstanding Reviewer Award 2018

Toshimori Honjo

Atsushi Ishizawa, Tadashi Nishikawa, Kenichi Hitachi, Hideki Gotoh

JSAC Female Analyst Award

Outstanding Reviewer for Semiconductor Science and Technology in 2018

Yuko Ueno

Xuejun Xu

Certificate of Award for Encouragement of Research in the 29th Annual Meeting of MRS-J Symposium L
Creation of Tough Hydrogel Architectures Towards Obtaining Hydrogel Fluidic Devices

JSAP Young Scientist Presentation Award

Radiative lifetime of bound excitons in GaAs with vibrational strain

Riku Takahashi

Ryuichi Ohta

JSAP Young Scientist Presentation Award

Jeff=3/2 ferromagnetic insulating state above 1000 K in a double perovskite osmate synthesized by molecular beam epitaxy

JSAP Young Scientist Presentation Award

Directed aggregation of cardiomyocytes by topographical guides in co-culture system

11

Hiroki Miyazako

Yuki Wakabayashi