QUANTUMNETWORKWHITE PAPER

2021

Copyright © 2021 NICT All Rights Reser ved.

2035

Quantum Network White Paper(0.9 version)

National Institute of Information andCommunications Technology (NICT)
April 2021

2

Table of Contents
CHAPTER 1: INTRODUCTION ........................................................... 5
1. ABOUT THE WHITE PAPER ................................................................... 5(1) Objective ................................................................................... 5(2) Overview of white paper ......................................................... 5(3) Discussion team and schedule .............................................. 5
2. INTERNATIONAL TRENDS AND THE OVERVIEW OF QUANTUM INFORMATIONCOMMUNICATIONS .................................................................................. 6(1) Overview of quantum information communications ............ 6(2) Policies and R&D trends regarding quantum ICT ................ 7(3) Quantum cryptography ......................................................... 10(4) Quantum network .................................................................. 12(5) Quantum Internet .................................................................. 13
CHAPTER 2 : IMAGE AND USE CASES OF A SOCIETY REALIZEDBY QUANTUM NETWORKS ............................................................. 16
1. IMAGE OF SOCIETY REALIZED BY QUANTUM NETWORKS ......................... 16(1) Overview .................................................................................. 16
2. IMAGE OF SOCIETY AND USE CASES REALIZED BY QUANTUM KEY
DISTRIBUTION (QKD) NETWORKS .......................................................... 17(1) Information to be protected by the QKD network............. 17(2) Image of society and use cases realized by QKD ............. 18(3) Examples of use cases in individual fields ......................... 19
3. IMAGE OF SOCIETY AND USE CASES REALIZED BY QUANTUM NETWORKS . 24
(1) Image of society and use cases ........................................... 24(2) Examples of use cases in specific fields ............................ 24
CHAPTER 3 : QUANTUM NETWORK EVOLUTION ......................... 27
1. IMAGE AROUND THE YEAR 2025........................................................ 27
2. IMAGE AROUND THE YEAR 2030 ....................................................... 28
3. IMAGE AROUND THE YEAR 2040 ....................................................... 29
CHAPTER 4 : ELEMENT TECHNOLOGIES AND REQUIREMENTS . 32
1. OVERVIEW OF QUANTUM NETWORK TECHNOLOGY ................................. 32(1) Overview of elemenatl technologies ................................... 32(2) Initiatives at NICT .................................................................. 34
32. ELEMENTAL TECHNOLOGIES AND REQUIREMENTS ................................. 34(1) Quantum key distribution (QKD) network .......................... 34(2) Satellite and spatial communications ................................. 41(3) Quantum network .................................................................. 44
CHAPTER 5 : R&D ROADMAP ....................................................... 54
CHAPTER 6 : PROMOTION STRATEGY ......................................... 56
1. OVERVIEW ........................................................................................ 56
2. INDIVIDUAL PROMOTION STRATEGY ................................................... 56(1) Research and development .................................................. 56(2) Social implementation ........................................................... 57(3) International cooperation ..................................................... 58(4) System design ........................................................................ 59(5) Human resource development ............................................. 60
CHAPTER 7 : CONCLUSION .......................................................... 62
REFERENCE .................................................................................... 62

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Chapter 1: Introduction
1. About the White Paper(1) Objective
・ At present, efforts are underway in Japan and overseas todevelop quantum cryptography and quantum networks (theultimate goal is the "Quantum Internet"). In January 2020, theJapanese government released the "Quantum Technology
Innovation Strategy." NICT has been promoting cutting-edge R&D
related to quantum networks. In addition, NICT, as the "Quantum
Security Hub” in the Strategy, started promoting to create a hub
for industry-academia-government collaboration and to develop
human resources from FY2020.
・By releasing this white paper, we would like to show the directionof NICT's research and development as the hub of quantum
security and the issues to be tackled in the future, to attract
international
researchers,
topromotecooperation
withinternational research institutes, and to accelerate research anddevelopment toward quantum networks.
(2) Overview of the white paper・ This white paper consists of international trends of quantum
communication, the image of society and use cases to be realized
by quantum networks, the R&D roadmap and promotion strategy
that NICT will work on to realize the society and the use cases.
This white paper is published as the first edition.
・The ultimate goal of this white paper is the "Quantum Internet".
In order to understand the importance of collaboration among
various stakeholders in Japan and overseas, as well as researchand development efforts, this paper is intended for virous readers,
including governments, companies, universities, and research
institutions.
(3) Discussion team and schedule・ This white paper was the result of discussions among NICT
researchers in the fields of quantum ICT, future ICT, spacecommunications, and networks, as well as NICT officials working
5

on the promotion of quantum networks, over a period of 5 months
from November 2020 to March 2021.
2. International trends and the overview of quantum information
communications(1) Overview of quantum information communications
・Information and communications technology, such as the Internet,
supports the development of the world's economy and society, andis a source of industrial competitiveness.
At present, we are in the midst of digital transformation (DX) in
COVID-19 pandemic, and the social change is progressing by
utilizing information and communications networks.
・ On the other hand, cyber-attacks on information andcommunications networks continue to increase, and therealization of safe and secure information and communications
infrastructure is required.
・It is feared that modern cryptography used in modern informationand communications networks will be compromised by the highperformance of quantum computers being developed by major IT
companies in the United States. The National Institute ofStandards and Technology (NIST) in the United States isinvestigating and evaluating post-quantum cryptography. It is alsofeared that there will be an attack in which encrypted data flowing
through the current information and communications networks areeavesdropped/obtained, and then decrypted when a highperformance quantum computer is put into practical use (harvest
now, decrypt later).
・For this reason, quantum cryptography is required as a technology
to realize "information-theoretic security" that is impossible todecrypt by any computer in principle. Several countries such as
the United States, Europe, and China, including Japan, are rapidly
promoting R&D, demonstration for practical application, andconstruction of quantum cryptography networks for actual
operation.
・ The Beyond5G/6G, for which R&D activities have started invarious countries around the world, has "ultra-security andreliability" as one of its functional requirements, and quantum
6

cryptography is expected to play an important role here as well.
・Research and development of quantum computing and quantum
sensing technologies are currently underway in Japan andoverseas. In the future, it is expected that these technologies will
be put into practical use and connected to quantum networks,
enabling ultra-large-scale information processing and ultra-highprecision information collection (see Chapter 2). Basic research is
being conducted in Europe and the United States with the aim ofcreating so-called the "Quantum Internet," in which quantum
information devices are connected to quantum networks.
・ The quantum internet is expected to become a new social
infrastructure by realizing new applications and services that havenever been seen before. Research and development of quantum
networks and efforts to implement quantum networks in society
have become important initiatives that are directly linked toensuring national economic and social prosperity and national
security.
(2) Policies and R&D trends regarding quantum ICT・ Foreign countries such as the United States, Europe, and China
have formulated R&D strategies for quantum information
communications, including quantum key distribution and quantum
networks, as strategic core technologies, and are making largescale R&D investments. In addition, these countries are promoting
strategic initiatives such as forming R&D hubs and developing
human resources.
① Policy and R&D trends in the United States・ In the United States, based on the “National Initiative Act”
(2018), the Department of Energy (DOE) and the National Science
Foundation (NSF) are investing $1.2 billion over five years inresearch and development of quantum information science from along-term perspective on a science-first approach. In this context,
the DOE and the NSF are collaborating with universities,
companies, and other organizations to promote research,development, and demonstration of elemental technologies andhuman resource development for the realization of the quantum
7internet. The Office of Science and Technology Policy (OSTP), in
its "Strategic Vision for U.S. Quantum Networks" (February 2020),
has identified six areas of research activity that should betargeted and focused on for the quantum internet, as well as goals
for the next five and 20 years. The DOE held “Quantum Internet
Blueprint Workshop” (July 2020) to discuss the direction andmilestones of research and development for the quantum internet.
② Policy and R&D trends in Europe
・In Europe, the European Commission has pledged to invest € 1.0
billion over five years in the "Quantum Flagship" (since 2018) to
conduct R&D on quantum technologies. In March 2020, theEuropean Commission released the “Strategic Research Agenda on
Quantum Technology” with the ultimate goal of the quantum
internet, which includes a roadmap for R&D, industrialization,
standardization, and human resource development. In addition, 25
countries in Europe have agreed to develop a quantum
communication infrastructure, “EuroQCI”, which would lead to theconstruction of the quantum internet network. In addition, theCommission is promoting the construction and demonstration of a
QKD testbed through the “OpenQKD” project.
・European governments, including the United Kingdom, Germany,and France, are also promoting R&D of elemental technologies for
QKD and the quantum internet.
③ Policy and R&D trends in China
・ In China, a quantum cryptography communication backbone
connecting Beijing and Shanghai and metropolitan area networks
in major cities have been constructed. The total length of thequantum cryptography networks have reached more than 7000 km
as of 2018. A number of companies have been established toprovide communication equipment, devices, and platforms. In
addition, China launched the "Mozi" satellite in 2016 andsuccessfully demonstrated a quantum cryptosystem between thesatellite and the earth. In January 2021, China released to conduct
a demonstration of an integrated quantum network between asatellite and the ground to promote the deployment of an
8integrated quantum cryptography network across China.
④ Policy and R&D trends in Japan・In Japan, in 2018, the Cabinet Office launched the second phaseof the Strategic Innovation Program (SIP), the Ministry of
Education, Culture, Sports, Science and Technology launched the
Optical and Quantum Leap Flagship Program (Q-LEAP), theMinistry of Economy, Trade and Industry launched quantum
computing (quantum annealing computer, etc.), and the Ministryof Internal Affairs and Communications started research anddevelopmentofquantum
cryptographyforsatellite
communications.
・On the other hand, these efforts are individual R&D initiatives
undertaken by relevant ministries, agencies, and companies.
These initiatives are not necessarily consistent. Therefore, the"Quantum Technology Innovation Strategy" (January 2020) wascompiled and published to promote quantum technology
innovation by mobilizing the collective efforts of industry,
academia, and government in Japan.
・ Based on the Strategy, eight quantum technology R&D hubs
(Quantum Computer R&D Hub (RIKEN), Quantum Device R&D Hub(National Institute of Advanced Industrial Science andTechnology: AIST), Quantum Computer R&D Hub (University ofTokyo and Corporate Consortium), Quantum Software R&D Hub(Osaka University), Quantum Security Hub (National Institute ofInformation and Communications Technology: NICT), Quantum
Material R&D Hub (National Institute for Materials Science: NIMS),
Quantum Sensor Hub (Tokyo Institute of Technology), andQuantum Chemistry Hub (National Institutes for Quantum andRadiological Science and Technology ： QST)) are currently
conducting quantum technology
・In 2020, the Cabinet Office started research and development of
quantum technologies, including quantum communications, underthe “Moonshot Research and Development Program”, and theMinistry of Internal Affairs and Communications started researchand development toward the creation of a global quantum
cryptography network.
9・ NICT, as the "Quantum Security Hub", is conducting andpromoting research and development of quantum cryptography
and other key technologies for quantum networks.
(3) Quantum cryptography[What kind of technology?]
・Quantum cryptography is a technology that uses the propertiesof quantum mechanics to make cryptographic communication
unbreakable by any computer. It consists of two steps: quantum
key distribution (QKD) and one-time pad encryption. QKD is amethod of sharing symmetric cryptographic keys between two
remote locations without revealing any information to a third party(eavesdropper) with any theoretical ability. In one-time pad
encryption, a cryptographic key of the same size as the data(plaintext) is prepared, and a ciphertext is generated by the XORof the plain text and the cryptographic key. The cryptographic key
is discarded once by once, without reusing it. In this way,
cryptographic
communications
with"information-theoretic
security" that cannot be deciphered in principle by any computer
including quantum computers can be realized.

Figure 1 : Mechanism of Quantum Cryptography

10[For what / why necessary?]
・ The cryptography which widely used today securesconfidentiality in "computational security," which requires a hugeamount of computing power to decrypt them. However, there is apotential threat that decryption will become easier in the futurewith the emergence of quantum computers and completely newcomputing technologies and mathematical algorithms. In particular,
in the case of critical information that requires confidentiality for
decades, a malicious third party may launch a so-called "harvest
now, decrypt later" attack, in which encrypted data iseavesdropped and obtained for the time being, without having thetechnology to decrypt it, and the encrypted data is decrypted
after establishing new computing technology in the future.
・ On the other hand, quantum cryptography has informationtheoretical security that cannot be decrypted in principle by any
computer in the future. The only cryptographic technology that
can achieve information-theoretical security is quantum
cryptography at present. In this sense, quantum cryptography canachieve the strongest level of confidentiality among currently
known cryptographic technologies. Quantum cryptography can beused to protect national secrets in such as national security, andtoprotect
informationthatrequiresultra-long-term
confidentiality in fields such as medical, finance, infrastructure,and smart manufacturing.
[International trends]
・ Research and development and social demonstrations areprogressing in countries such as Japan, Europe, the United States,
China, and South Korea, and international standardization and fullscale practical application are starting.
[Requirements that may be required]
・It is necessary to establish a QKD network technology that allows
a large number of QKD transmitters and receivers to be connectedto the network and operated safely and efficiently.
・ By sharing the encryption key at any two points (or multiple
points) through the QKD network and using the key at the11

conventional network (the classical network), security services
using the information-theoretically secure encryption key are
realized.
(4) Quantum network[What kind of technology?]
・ A quantum network is the communication infrastructure for
distributing quantum information (quantum bits used in quantum
computers, quantum entanglement state with quantum correlation,etc.) over networks instead of classical digital information (0,1),
and is utilized for various applications.
・Distribution of quantum information through a quantum network
is expected to enable quantum cryptography over longer distances
than currently possible, as well as a quantum network of opticalclocks (atomic clocks that generate precise optical signals) thatcan be connected to each other to keep time with an accuracy thatis impossible with conventional technology.
・ Moreover, by connecting multiple small- and medium-scalequantum computers to a quantum network, it would be possible tobuild a large-scale quantum computer with high computing power(distributed quantum computing). Furthermore, by connecting alarge-scale quantum computer at a remote location to a quantum
network, it is expected to be possible to perform secret quantum
computation without anyone knowing the contents of thecomputation.
[International trends]
・ Basic research on quantum physics, which is an elemental
technology on a quantum network, has been conducted around theworld. In Europe and the United States, efforts to demonstrate theoperation principle in the field has started since around 2020, andin Japan, studies have started to build a testbed on a quantum
network.
[Requirements that may be required]・ To realize a quantum network, the following elemental
technologies are required:quantum memory technology for12storing and processing quantum information, quantum interface
technology for connecting optical signals and quantum memory,and quantum relay technology for relaying and transmitting
quantum information (especially quantum entanglement) without
destroying it. All of these technologies are still in the basic
research stage, and trial and error is still being conducted withvarious material materials and candidate relay methods.

Figure 2 : quantum networks overview(5) Quantum Internet
・The definitions of the "Quantum Internet" are described as in thetable below in the research strategies and projects on quantum
technology in the United States and Europe.
・The “Quantum Internet" is a global quantum network to whichquantum information equipment and devices such as quantum
computers and quantum sensors are connected. Also, given thatthe current Internet is a network in which multiple networks areinterconnected and digital information (bits) are distributed, the"Quantum Internet" is a network in which multiple "quantum"
networks are interconnected and "quantum information (qubits)"
are distributed."・ In the future, it is expected that the definition of "Quantum
Internet" will be clarified in the process of maturation of elemental
technologies of "Quantum Internet" through international
discussions.
・ When the Internet first appeared, no one imagined that theInternet would become indispensable infrastructure for socioeconomic activities and people's lives as it is today. At this point13

of time, it is not clear what kind of network the "Quantum Internet"
would be and how it would be used. However, it is expected that
future applications and services that cannot be imagined atpresent will be provided on the "Quantum Internet" in order tomake people's lives richer, safer and more secure.
Document/

Definition example

OrganizationThe”A STRATEGIC VISION FOR

the quantum internet—a vast network of

UnitedAMERICA'S QUANTUM

quantum computers and other quantum

StatesNETWORKS” （2020.2）,

devices the quantum internet-a vast

National Quantum

network of quantum computers and other

Coordination Office, White

quantum devices

House "A STRATEGICVISION FOR AMERICA'SQUANTUM NETWORKS"(2020.2), National Quantum
Coordination Office, WhiteHouse“Quantum Internet Blueprint

The international research community

Workshop” (2020.10),

perceives the construction of a first

Department of Energy

prototype global quantum network—the（DOE） "Quantum Internet

Quantum Internet—to be within reach over

Blueprint Workshop"

the next decade.

(2020.10), Department ofresearch community perceives theEnergy (DOE)

construction of a first prototype global

The international

quantum network-the Quantum Internet-to
be within reach over the next decade.
EuropeQuantum Internet

The long-term ambition of the European

Alliance(QIA) Quantum

Quantum Internet Alliance is to build aInternet Alliance(QIA)

Quantum Internet that enables quantum
communication applications between any
two points on Earth The long-term ambitionof the European Quantum Internet Allianceis to build a Quantum Internet that enables
quantum communication applications
between any two points on Earth

14

“Strategic Research Agenda“Quantum Internet”: quantum computers,on Quantum Technology”

simulators and sensors interconnected via(2020.3), Quantum Flagshipquantum networks distributing information

Project "Strategic Researchand quantum resources such as coherence

Agenda on Quantum

and entanglement to secure our digital

Technology"(2020.3),

infrastructure. "Quantum Internet":

Quantum Flagship Project

quantum computers, simulators andsensors interconnected via quantum
networks distributing information andquantum resources such as coherence andentanglement to secure our digital
infrastructure.

Standard-

IRTF （Internet Research

Quantum Internet - A network of Quantum

izationTask Force） IRTF (Internet

Networks. The Quantum Internet will bebody

Research Task Force)merged into the Classical Internet to form a
new Hybrid Internet. The Quantum Internet
may either improve classical applications
or may enable new quantum applications.
Quantum Internet - A network of Quantum
Networks. The Quantum Internet will bemerged into the Classical Internet to form a
new Hybrid Internet. The Quantum Internet
may either improve classical applications
or may enable new quantum applications.

Table 1 ： Examples of quantum internet definition

15

Chapter 2 : Image and Use Cases of a Society Realized
by Quantum Networks
1. Image of society realized by quantum networks(1) Overview
・The following is examples of the use cases that are expected tobe realized by quantum networks in the future.
・ In the 2020s, QKD networks are expected to enable secureexchange of critical information in the medical, manufacturing,and financial fields.
・ In the 2030s and beyond, the spread of QKD networks is
expected to enable the safe and secure distribution of information
in a wider variety of fields. In addition, quantum networks
connected with quantum computers and quantum sensors will
begin to be deployed in society.
・In the 2040s, the “Quantum Internet”, in which multiple quantum
networks are globally connected to each other, will be established,
and new applications and services will emerge that have neverseen before. The "Quantum Internet" is expected to become thefoundationthat
supports
people's
affluent
lives
andsocioeconomic activities.

16

Example of use case ● : QKD, ★ : Quantum computer, ▲ : E quantum sensing

Table 2: Quantum Networks Use Cases (Overview) 1
2. Image of society and use cases realized by quantum key
distribution (QKD) networks(1) Information to be protected by the QKD network
・Security, diplomacy, defense, and personal genome information,
all of which a significant impact if leaked, must be protected overa long period of time. When sending such information over a
network, it is expected that QKD, which guarantees informationtheoretical security, will be used.

1

https://www.ibm.com/blogs/think/jp-ja/ibm-quantum-roadmap/

17

Information
holderExamples of information to be protected

National/ local

・Diplomatic info, defense info, security info, geographicalgovernments

info. (infrastructure, underground space), family register/ resident info, voting info, etc.

Organization

・Customer lists, new business plans, price info, response(Enterprises,manuals, etc. (sales info.)etc.)

・New technologies, manufacturing methods, know-how,design drawings, etc. (technical information) , etc.

Individual

・ Health info, genome info, ideas, beliefs, preferences,personal identification numbers, credit card numbers,
passwords, etc.

Table 3 ： Examples of information to be protected by QKD(2) Image of society and use cases realized by QKD・ Deployment of QKD will enable theoretically securecommunications in medical, industry , services, government,
diplomacy, , security, and daily life.

Figure 3 : Examples of Use Cases Realized by QKD
18

(3) Examples of use cases in individual fields①Medical and Financial Fields ~ Secure Data Distribution / Storage/ Utilization with Quantum Secure Cloud ~・It is an important task to store large amounts of information,
which is one of the important management resources of a company,
using encryption and other methods, and to decrypt themcompletely as necessary.
・At present, communication can be secured by current encryption
technology. However, with the advancement of quantum
computers, there is a risk that the encryption used for highly
secure information communication for electronic payments andthe exchange of personal information will be broken. Therefore,
encryption technology that will never be broken is required.
[Technical outline]
・ Quantum secure cloud technology is a cloud technology thatenables secure distribution, storage, and utilization of data by
integrating quantum cryptographic technology, secret sharing
technology, and post-quantum cryptographic technology. QKD
networks and secret sharing enable information-theoreticallysecure data storage and communication. The authentication
infrastructure(post-quantum/public
keyauthentication
infrastructure) based on post-quantum cryptography, which
require an enormous amount of computation to decipher, is used
to authenticate users on the network and issue signatures toprevent tampering.
・The establishment of quantum secure cloud technology will not
only ensure high security that cannot be tampered with or
deciphered, but will also enable the collection, analysis,
processing, and use of highly confidential data, such as personaland corporate information accumulated in the medical, newmaterials, manufacturing, and financial fields.

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Figure 4 : Mechanism of quantum secure cloud technology②Administration, diplomacy and security ～Secure core networkwith satellite QKD～
[Background and necessity]
・QKD network needs to spread across Japan and across continents
in order to securely exchange information related to national
security and confidentiality, as well as personal information in
local governments, across a wide area such as between cities andcountries.
・However, QKD is vulnerable to signal attenuation in principle,
which makes long distance transmission of quantum cryptographyusing optical fiber difficult. Therefore, satellite-based quantum
cryptography communication networks in space, in which signal
attenuation is lower than that of optical fibers, play an importantrole to realize a wide-area QKD network.
・In addition to the link between geostationary orbit satellites andthe ground, the QKD backbone network based on satellite QKD
enhances robustness and availability by utilizing multiple
satellites (constellation satellites) in low and medium earth-orbit
20and cooperation with the terrestrial QKD network.
・In the future, it is expected to play a role as infrastructure for
exploration
anddevelopmentbyestablishing
quantum
communication links with the Moon and Mars.

Figure 5 ： Secure backbone network with satellite QKD③ Industry and service area ～Local secure network by opticalspace communication～[Background and necessity]
・ The trade secrets, know-how, and technical information thatcompanies have accumulated over many years are important
information in the industrial and service sectors. One of ways toprotect this information from information leakage by industrial
espionage is to use a local secure network using free space optical(FSO) communication, which can be built independently bycompanies on a scale of their premises, office buildings, and major
branch offices.

21

[Technical outline]
・A secure network that can be built independently by companies
is required to : (1) be able to be built independently of externalorganizations ; and (2) be able to be built at low cost. Among
several QKD protocols, CV-QKD (Continuous Variable - Quantum
Key Distribution), a system that is expected to be able to be built
at low cost with the equipment and components used in current
optical communications, can be implemented in optical spacecommunications.
By
implementing
thissystemin
FSO
communications, a secure network that satisfying the above
requirements can be built without procuring and installing new
optical fibers. In addition, by combining this system with securecommunications (physical layer cryptographic communications)(see Chapter 4), which utilizes the unique characteristics of
optical space communications, i. e., the spatial divergence of lightis smaller than that of radio waves, making it difficult for third
parties to eavesdrop, it is possible to build a network that can meetvarious user requirements.

Figure 6 ： Local Secure Network with QKD and Physical Layer
Encryption④ Daily life ～Highly secure infrastructure available to everyone～[Background and necessity]
・ With the development of 5G technology, as services via mobile
devices become more prevalent in people's lives, personal security
risks including leakage of important information in everyday
22

life(e.g., passwords, credit card numbers, and health information),takeover of smart devices (e.g., network cameras, smart
appliances, and smart speakers), will emerge. In order to ensure
security at individual level, greater consideration is required to
avoid differences in security level between individuals andorganizations such as security providers.
・Therefore, we need a new security infrastructure that updates
the security technology used in the current security infrastructure.
[Technical outline]
・ In this infrastructure, key exchange and authentication on aconventional network (classical network) is carried out by
cryptographic technology (post-quantum cryptography) that isdifficult to break even by quantum computers. Communication
between a mobile terminal and an access point is carried out byphysical layer cryptography, which further enhances security of
networks. Since these technologies can be implemented asalgorithms on mobile terminals, individuals can use thisinfrastructure without being forced to bear a heavy burden.

Figure 7 : New security infrastructure with post quantum
cryptography infrastructure23

3. Image of society and use cases realized by quantum networks(1) Image of society and use cases
・ It is expected that the realization of quantum networks (theQuantum Internet) will lead to the realization of safe, secure andconvenient lifestyles and advanced socioeconomic activities.

Figure 8 : Examples of image of society and use cases realized byquantum networks(2) Examples of use cases in specific fields①Quantum Sensing ～Disaster Prevention and Disaster Response～[Background and necessity]
・ By connecting optical clocks (an example of the quantum
sensors), which can provide high-precision timing and local gravity
sensing, to a quantum network, and sending detected information
on gravity field fluctuations such as earthquakes, volcanic
eruptions, and landslides via the quantum network, it will bepossible to issue disaster warnings earlier than before.
・In addition, the realization of highly accurate time and space24synchronization is expected to lead to the emergence of nextgeneration communication systems and new time businesses.
[Technical outline]
・ In order to transmit information such as gravitational field
fluctuations detected by an optical clock using a quantum network,a technology called coherent link is a prerequisite. The coherent
link is a technology to compare and synchronize the optical clocks
by connecting their optical frequencies as light waves. The
quantum network of optical clocks enables the fastest
measurements of the optical frequencies of the clocks allowed byphysics by adding it to the coherent link.
・In addition to the coherent link, other elemental technologies
such as optical clocks capable of quantum gate operation,
quantum interfaces with photons, and two-photon interference
will be required.

Figure 9 : Use cases of quantum networks for optical clocks② Distributed Quantum Computing ～Chemistry, Materials, Drug
Discovery, etc.～[Background and necessity]
・Quantum computers will make it possible to simulate ultra-large
scale molecular structures, which has been difficult withconventional supercomputers, and is expected to lead to drug
discovery, materials with new functionalities, and new use cases
for future social infrastructure.
・Furthermore, by connecting quantum computers to a quantum
25

network, it will be possible to accelerate the development of largescale quantum computers.
・Since such large-scale quantum computation is expected to beprovided by cloud services, a method to perform quantum
computation while keeping the computation secret is required.
Using a small-scale quantum computer connected to a large-scalequantum computer by a quantum network is expected to makesuch blind quantum computation possible.
[Technical outline]
・ Quantum computing is a computational method that uses
quantum bits (qubits) based on quantum physics instead ofclassical digital bits (0,1) to rapidly solve certain computational
problems with computational resources that grow exponentiallywith the number of qubits (called "Hilbert space"). Distributed
quantum computing is a method of extending quantum computing
by connecting quantum computers in a quantum network.
・In order to connect quantum computers at the qubit level in aquantum network, a wide range of technologies are required. They
include research and development of quantum repeaters andquantum network technologies for sharing quantum entangledstates over optical fibers, as well as technologies for constructing
small- and medium-scale quantum computers.

Figure 10 ： Use cases for distributed quantum computer
networks
26

Chapter 3 : Quantum Network Evolution
・Chapter 3 describes the evolution of quantum networks by the2025s, 2030s, and 2040s.
・ Quantum networks using QKD and quantum relays will be
introduced step by step as the technology development andimplementation. However, it does not mean that conventional
networks such as the Internet and cell phone networks (classicalnetworks) will be replaced by quantum networks, but rather thatclassical and quantum networks will coexist. The coexistence ofclassical networks and quantum networks will enable therealization of the various services described in the previous
chapter. The following is an overview of the evolution of quantum
networks.
1.Image around the year 2025
・ The service operation of the quantum key distribution (QKD)
network connecting the ground and satellite is expected to start,
and that the secure communication service is expected to beprovided. It is also assumed that the service using quantum
computing and quantum sensing using classical networks is
expected to be launched.

27

Figure 11: Evolution of quantum networks around 2025 2

2. Image around the year 2030
・The operation service of QKD networks connecting terrestrial andsatellites secure communications services is expected to expand.
In addition, services using quantum computing, quantum
measurement and sensing over classical networks are expected to
expand.

2

PKI：Public Key Infrastructure, TLS: Transport Layer Security(A mechanism forensuring a secure communication path for communication on the Internet)

28

Figure 12 : Evolution of quantum networks around 20３0
3. Image around the year 2040
・ It is assumed that a global quantum network of satellites andterrestrial networks will be established, and that a virtual quantum
network service will be realized to accommodate a wide varietyof quantum networks and protocols.

29

Figure 13: Evolution of quantum networks around 2040
・It is also assumed that infrastructure providers and quantum
virtual network operators (VNOs) will construct virtual quantum
networks and provide services in response to the requirements ofapplication/content providers using quantum networks around
2040.

30

Figure 14 : Image of services in quantum networks around 2040

31

Chapter 4 : Element Technologies and Requirements
1. Overview of quantum network technology(1) Overview of elemental technologies
・The chart below shows the elemental technologies of quantum
networks in the "Quantum Technology Innovation Strategy"(January 2020). Of these, NICT is conducting R&D on technologies
in red in the chart below.

32

Figure 15 : Overview of quantum network technologies
33(2) Initiatives at NICT・ NICT is conducting R&D on quantum key distribution (QKD)
networks, satellite and space communications, and quantum
networks. The next section gives an overview of these elemental
technologies and requirements.

Figure 16 : R&D on quantum network technologies at NICT
2. Elemental technologies and requirements(1) Quantum key distribution (QKD) network[Overview]
・A QKD network is a technology that makes it possible to sharecryptographic keys to any two (or more) points in a network. The
cryptographic keys shared in a QKD network are used for
cryptographic communications in conventional networks (theInternet, mobile communication network, etc.) in which several
application services are provided . In other words, by adding the
QKD network to the conventional network, it is possible to provide
a secure cryptographic key for a very long term. One of theapplications of the QKD network is quantum secure cloudtechnology.
34

[Required Technologies]
・In addition to QKD equipment(QKD transmitters and receivers,
called QKD modules), element technologies such as key
management / key relay, QKD network control / management, arerequired. In addition, it is necessary to establish node security(trusted node).

Figure 17 ： QKD network configuration[International trends]
・Demonstration and test operations are underway in the UnitedStates, Europe, China, and South Korea, as well as Japan. The"Tokyo QKD Network," a testbed built in 2010 by Japanesecompanies, has the longest history of operation in the world.
As for QKD equipment, ID Quantique (Switzerland), Quantum
CTek (China), Toshiba (Japan) and others have started
commercialization and operation services, and NEC (Japan) is in
the field test stage. In addition, a number of start-ups aredeveloping QKD devices in various countries. QKD network
35

services are also being commercialized by companies such as CAS
Quantum Network (China) and Quantum Xchange (USA).
Incumbent telecommunications companies such as BT (UK),
Verizon (USA), and SK Telecom (Korea) are also entering themarket.
[Reference] International standardization of QKD network
technology
・NICT is actively promoting international standardization at theInternational
Telecommunication
Union
Telecommunication
Standardization Sector (ITU-T) and the International Organizationfor Standardization / International Electrotechnical Commission(ISO/IEC) to promote the global spread of QKD network
technology in cooperation with governments and companies.
・In October 2019, ITU-T published "Y. 3800 Overview on networks
supporting quantum key distribution," the first international
standard recommendation in the field of quantum cryptography,
adopting the basic specifications of the Tokyo QKD network.
Starting with this recommendation, ITU-T has published more than
10 recommendations. Japan is also leading the development ofthese recommendations.
・At ISO/IEC JTC1, NICT is actively participating in the developmentof standards for the safety assessment of QKD devices. Since QKD
devices are security devices, it is necessary to develop safety andoperational guidelines, as well as evaluation, testing, andcertification framework to ensure that commercialized QKD
devices are implemented and operated correctly from theviewpoint of safety, in order to properly distribute QKD devices in
the market.

36

Figure 18 ： Basic configuration of the QKD network specified in
ITU-T Y. 3800 3
・The following is a description of the elemental technologies
required for QKD network and its application, quantum secure
cloud technology.
① Quantum key distribution (QKD)[What kind of technology?]
・It is a technology to share encryption keys between two distantparties using photons, which are particles of light. Due to theuncertainty principle of quantum mechanism, any eavesdropping
attack on photons can be certainly detected, By using
cryptographic keys that is not eavesdropped, informationtheoretically secure cryptographic keys can be generated. On theother hand, since photons are extremely weak signals andordinary optical communication relay amplifiers destroy thequantum state of photons, the distance over which a pair of QKDtransmitter / receiver can generate a key is currently limited to3

Abbreviations in Figure18

QKDN: QKD Network, KM: Key Manager

3750-100 km at the most.
② Key management and key relay technology[What kind of technology?]
・Key management is a technology that securely manages keys
generated by QKD equipment and appropriately supplies them toapplications. Key relay is a technology that securely transmits
keys generated by QKD equipment to remote nodes through onetime pad encryption and a cryptographic key generated byanother QKD equipment. By combining these technologies with
node with guaranteed security (trusted node), long-distance key
generation and QKD networking, which are impossible with asingle QKD transmitter and receiver, are realized.

Figure 19 ： Quantum key relay mechanism③ QKD network control and management technology[What kind of technology?]
・The QKD network control technology is comprised of session
control between sending and receiving hosts , access control, key
relay routing and rerouting, policy control, network configuration
control, etc. in the QKD network. The QKD network management
technology appropriately manages the entire network bymonitoring the status of network components and links in the
QKD network. It is expected that conventional network control
andmanagement
technologies,
suchas
networkvirtualization/automation technology and information-centric
networking technology, can be applied to the QKD network invarious ways and thus, enable the network to efficiently deliver38

cryptographic keys with the required size and security level tousers at any time.
④ Quantum secure cloud technology[What kind of technology?]•This technology enables data backup storage and computation
processing that cannot be deciphered or tampered by any
computer, by integrating quantum cryptography, secret sharing,post-quantum/public key authentication infrastructure, andsecure computing. Multiple data servers are connected by secretlines using quantum cryptography to form a storage network, andsecret sharing algorithms are implemented to the network torealize information-theoretically secure backup storage of theoriginal data.
・In this way, the system provides both confidentiality, in which
the original data cannot be recovered even if information is stolen
from some of the data servers, and availability, in which the user
can recover the original data by collecting distributed data fromthe remaining data servers even if some of the data servers arelost due to a disaster.
・In addition, it enables secure secondary use of the data, since it
is possible to realize secure computing by processing the data inthe meaningless distributed data.
・ User authentication and data falsification prevention are
performed using certificate with digital signatures issued fromthe post quantum -public key authentication infrastructure. The
post quantum - public key authentication infrastructure is one of
the next-generation cryptographic infrastructures that are
expected to spread in the future and is based on computational
security. For user authentication and prevention of data
falsification on quantum secure clouds, the post quantum - public
key authentication infrastructure is utilized because it issufficient to secure security within the time required forprocessing.
・ In this way, the entire system is configured by combining
appropriate security technologies according to safety andconvenience.
39

Figure 20 ： Quantum secure cloud technology[For what / why necessary?]・ This technology is necessary to ensure ultra-long-term
confidentiality of data. For example, medical information such as
patient information and genetic data require ultra-long-term
confidentiality. On the other hand, there is concern about data
loss due to disasters, etc., if it is stored in only one hospital. It isalso an urgent issue to safely back up data in remote locations.
Quantum secure cloud can achieve both at the same time. (See"Mechanism of quantum secure cloud technology" on p.20)[International trends]
・This is a unique Japanese technology that is being demonstrated
by NICT and companies.
[Requirements that may be required]
・It is necessary to appropriately integrate the QKD network andvarious modern security technologies (secret distribution, secretcalculation, electronic signature, etc.) into a system.
40

(2) Satellite and spatial communications① Satellite Quantum Key Distribution (QKD) Technology[What kind of technology?]
・ It is a technology to share information-theoretically secure
cryptographic keys through quantum communication between
ground and satellite or between satellites. (See "Secure
backbone network with satellite QKD" on p.21.
[For what / why necessary?]・ In terrestrial QKD networks, the optical loss in optical fiber
prevents QKD from being transmitted over long-distance, so ahuge number of QKD devices and trusted nodes are required for
globalization. On the other hand, the atmospheric layer
surrounding the earth is about 10 km, and the optical loss inspace is very small. Therefore, satellite-to-ground communication
can greatly increase the transmission distance of QKD. Satellite
QKD is an essential technology for the globalization of QKD
networks.
[International trends]
・NICT has demonstrated quantum communication between a 50kg small satellite and a ground station, which is the basis of the
QKD 4. Meanwhile, China has succeeded in the QKD experiment 5
between a low-earth orbit satellite and the ground. The
momentum for accelerating satellite QKD research is growing
among governments, universities, and venture companies aroundthe world.
[Requirements that may be required]・In addition to the development of a new QKD protocol optimized
for satellite communications, it will be necessary to develop
pointing acquisition and tracking technology as well as adaptive
optics technology to stabilize the satellite-to-ground link, and

4
5

H. Takenaka, et al., Nat. Photonics, (2017)
S. –K. Liao, et al., Nature (2017)41

high-speed
andhigh-sensitivity
technology to detect photons.

single-photon

detector②Physical layer encryption technology[What kind of technology?]
・Unlike QKD, which is "secure against any physically allowableeavesdropping attack," physical-layer cryptography is atechnology for information-theoretically secure cryptographic
key establishment in situations where restrictions can be placedon eavesdroppers' attack models, such as "eavesdroppers
eavesdrop from outside the sight of the sender or receiver."(See "Secure core network with satellite QKD" on p21, "Local
secure network with QKD and physical layer encryption" on
p.22, and "New security infrastructure with post quantum
cryptography infrastructure " on p.23)[For what / why necessary?]
・This technology is used as a complementary technology to QKD
in communication systems such as satellite-to-ground andmobile communications, where the current QKD does notprovide sufficient performance or is difficult to implement.
[International trends]
・NICT is conducting physical layer cryptography research in freespace optical communications 6, and companies and universities
dealing with QKD have applied for patents on similar concepts 7.
[Requirements that may be required]・ In order to apply physical layer cryptography to satellite-toground communication, it is necessary to develop protocols,
technologies for establishing links such as pointing, acquisition
and tracking systems, and high-speed and high-sensitivity singlephoton detector technologies similar to satellite QKD technology.
6

H. Endo, et al., Opt. Express, (2018), H. Endo, et al., OSA Continuum., (2020)

7

M. Legre and B. Huttner, EP 3337063 A1, (2016)., E. J. A. Ling, et al., WO
2019/139544 A1, (2019). M. Legre and B. Huttner, EP 3337063 A1, (2016)., E. J. A.
Ling, et al., WO 2019/139544 A1, (2019).

42

On the other hand, in order to apply physical layer cryptography
to mobile communications, it is necessary to develop protocols
suitable for high-frequency bands (millimeter waves, terahertz
waves, and LEDs).
③ Satellite-terrestrial network coordination technology (adaptive
routing technology)[What kind of technology?]
・ This technology is used for continuously providing securecommunication services by selecting the optimum route andtransmission protocol (QKD/physical layer encryption, etc.) forthe entire satellite/terrestrial network, taking into consideration
user requirements such as the required level of security andnatural conditions such as weather. (See "Secure backbone
Network with Satellite QKD" on p.21)[For what / why necessary?]
・ For example, since satellite QKD / physical layer cryptography
cannot be provided in cloudy weather, it is necessary to select aground station in a sunny area. In order to provide secure service
without fatal delay, the terrestrial network route must also beappropriately changed according to this ground station selection.
[International trends]
・The change of ground stations based on weather conditions insatellite optical communications is called site diversity, and NICT
has been conducting R&D on this subject 8.
[Requirements that may be required]・ Technologies are required to collect information oncommunication channels such as weather information and shareit with satellite nodes and ground nodes. In addition,technologies are required to enable the miniaturization,
portability, and installation on ships of ground stations in orderto establish links with satellites at various locations on the
8

K. Suzuki, ICSO2014, or OBSOC

43

ground.
(3) Quantum network① Quantum interface[What kind of technology?]
・ It is a technology to transmit quantum information between
different
quantum physical systems without changing thequantum information. It is also called quantum media conversion.
[For what / why necessary?]
・It is needed to realize quantum connections via photons between
quantum systems of matter that constitute spatially separated
nodes.
[International trends]
・It has been reported that a fluorescent photon was generated
from a quantum system of matter and converted into acommunication wavelength band photon 9 , 10 . It has also beenreported that a quantum connection between two spatiallyseparated quantum systems of matter was formed via photons 11.
[Requirements that may be required]・A quantum entanglement manipulation technique is required togenerate quantum correlations between the matter quantum
system and the emitted photons. High performance photon
detectors are needed to measure the interference between thetwo photons generated at the sender and receiver with highefficiency. A quantum memory is needed to hold the quantum
state until the photons propagate, the interference measurement,
and manipulation into a quantum system of matter are performed.

9Phys. Rev. Lett. 120 203601 (2018).
Nat. comm. 9 1998 (2018). npj Quant. Inf. 5 72 (2019).
11
Phys. Rev. Lett. 119 010402 (2017), Nature 578 240 (2020).
(2015).
1044

Nature 526 682

Figure 21 ： Role of the quantum interface② Quantum repeater[What kind of technology?]
・It is a technology that enables quantum information transmission
over long distances by placing multiple quantum-connected nodes
at relay points.
[For what / why necessary?]・ In principle, quantum states cannot be replicated, so signal
attenuation due to loss in the communication channel cannot berecovered by amplification. Therefore, quantum repeater isnecessary to extend the distance of quantum connections. It isalso applicable to extend the distance of QKD.
[International trends]•In Japan and overseas, research and development of standard
methods consisting of quantum entanglement swapping, quantum
entanglement purification, and quantum memory is underway.
Improving the performance of quantum memory is considered tobe the key to realization 12 . In addition, an all-optical quantum
repeater protocol that does not use quantum memory has been
proposed in Japan 13 , and demonstration experiments areunderway 14.

12

Nature Photonics, 10, 381(2016)
Nature Communications 6, p. 6787(2015)
14
Nature Communications 10,378(2019)、Nature Photonics 13, 644 (2019)1345

[Requirements that may be required]・In addition to quantum entanglement control techniques such as
quantum entanglement swapping and quantum entanglement
purification, a quantum memory is required to maintain thequantum state until the end of the series of operations. In the alloptical quantum repeater protocol, quantum memory is not
required. High-performance photon detectors are required toobserve photon interference in quantum entanglement operations
with high efficiency.

Figure 22 ： Quantum repeater mechanism③ Multi-kind Quantum Network Control and Management[What kind of technology?]
・This technology enables the stable and inexpensive provision ofa wide variety of virtual quantum networks (including quantum
computer virtualization) that satisfy the requirements / demandsof various future applications, including QKD networks andquantum relay networks, on the same physical network.
[For what / why necessary?]
・ It is necessary to satisfy various application requirements /demands (cryptographic key size in QKD, communication
performance, stability of quantum applications, etc.) while
reducing costs by saving physical devices managed by network
operators.
46

[International trends]
・The ITU-T SG13 currently discusses software-defined network
control (SDN control) and virtualization for QKD networks 15. On theother hand, the IRTF currently discusses quantum internet(quantum relay network) 16 . In addition, several projects related toquantum networks have already been launched in Europe and theUnited States. In the United States, for example, the National
Quantum Coordination Office launched by White House Office of
Science and Technology Policy (OSTP) has published a report on
the National Strategy of Quantum Information Science 17. In Europe,
the Delft University of Technology in the Netherlands has
published a report on future quantum networks, including thequantum internet 18.
[Requirements that may be required]・In order to construct virtual quantum networks that satisfy therequirements and demands of various applications, and to respondto changes in conditions such as network traffic fluctuations andfault detection, it is important to achieve agility and effectivenessin route selection, rerouting, resource allocation, and so on. It will
enable the networks to enhance the stability of applications.
・Moreover, we can expect that it is effective to apply policy control(e.g.: SDN) and in-network computing technologies (e.g.:
information-centric networking and network coding 19) which havebeen actively researched and developed in classical networks.
・In addition, we will require advanced security technologies toensure the safety and security of control and management
mechanisms and also require integration of terrestrial- and
15

ITU-T SG13 Y.QKDN-SDNC (June 2020)
ITRF QIRG-ID: “Applications and Use Cases for the Quantum Internet”(draft-irtfqirg-quantum-internet-use-cases-04) (January 2021)
17“Quantum Frontiers: Report on Community Input to the Nation's Strategy for
Quantum Information Science, “ The White House National Quantum Coordination
Office (October 2020)
18“Creating the Quantum Future – QuTech Annual Report 2019,” Delft Univ. of Tech.
(March 2019)
16

19

K. Matsuzono, et. al., “Low Latency Low Loss Streaming using In-Network Coding andCaching”, Proc. IEEE Infocom (May 2017).

47

satellite-based network technologies to realize global virtualquantum networks in the future.

Figure 23 ： Quantum network mechanism④ Quantum sensor network (Quantum network of optical clocks
as an example))[What kind of technology?]
・Devices that use quantum effects to measure physical quantities
are called quantum sensors. Atomic clocks that use the opticalfrequencies are called optical clocks, and they are also used as
quantum sensors to measure gravity. Coherent links that connect
optical clocks with optical fibers or free space enable distributionof space-time information and gravity crowdsensing without
deploying quantum network technology. In a quantum network of
optical clocks, an extension of the link supported by quantum
connections, the measurement speed can be reduced to the limit
allowed by physical laws.
48

[For what / why is it necessary?]
・ It is required for the realization of high-precision timing
distribution
fornext-generation
communications,phasesynchronization for coherent optical communications, and ultralong baseline interferometry. As a gravity sensor, it is considered
to be effective for monitoring underground cavities, magma
reservoirs, and seafloor fluctuations.
[International trends]
・Construction of a coherent link with a total length of more than2000 km is in progress in Europe 20. In Japan, RIKEN, the Universityof Tokyo, NICT, and other organizations are conducting R&D on acoherent link. A link with a total length of 240 km has beenreported 21 . The quantum network of optical clocks has been
proposed only, and no actual implementation has been reported
so far 22.
[Requirements that will be required]・A coherent link that faithfully transmits the frequency accuracyof the optical clock is required. To plug in quantum connectivity, aquantum interface between atoms or ions and photons is required.
When the fiber length between optical clocks exceeds 100 km,
quantum repeaters are required.

20

https://www.clonets.eu/clonets-consortium.html

21

Optics Express,28,9186 (2020)

22

Nature Physics, 10, 583 (2014)49

Figure 24 ： Quantum network of optical clocks⑤ Quantum computing (Ion trap quantum computer)[What kind of technology?]
・An ion trap quantum computer consist of atomic ions laser-cooled
in an ion trap as qubits. All the qubits are connected via thephonons of the oscillating motion caused by the trap electric field
as a quantum bus. An ion trap quantum computer with a quantum
interface between ions and photons is called an opticallyconnected ion trap quantum computer.
[For what / why it is necessary?]
・A ion-trap quantum computer with a single ion trap is considered
to be limited to about 50 qubits due to fundamental and technicallimitations. Large-scale quantum computation is expected to bepossible by connecting multiple ion-trap quantum computers via
photons.
[International trends]
・In the U.S. and Europe, ion-trap quantum computers with up to
32 qubits without optical connectivity have been realized, andcloud quantum computing services have been launched 23. An iontrap quantum computer with optical connectivity has not yet been

23

https://ionq.com/, https://www.aqt.eu/

50realized, and research and development are underway in the
United States and Europe with the goal of achieving 50 qubits 24.
In Japan, research and development has begun under theMoonshot Research and Development program 25.
[Requirements that will be required]・We need a highly functional ion trap with a quantum interface
with photons that can perform quantum computation with about
10 qubits. Quantum wavelength conversion technology is required
to convert the wavelength of the photons generated by the ion
trap into the optical communication wavelength for connecting toan optical switch. Two-photon interference technology and highperformance photon detectors are required to perform opticalconnection operations.

Figure 25 ： Optically connected ion trap quantum computer⑥ Quantum computing (superconducting quantum computer)[What kind of technology?]・ Superconducting electric circuits cooled to cryogenic
temperatures behave quantum mechanically, and they are calledsuperconducting quantum circuits. Superconducting quantum
circuits have a high degree of freedom in their design, and can bemade into qubits, resonant circuits, waveguides, coupled circuits,
and so on. A superconducting quantum computer is a system

24

https://www.aqtion.eu/

25

https://www.jst.go.jp/moonshot/program/goal6/index.html

51

consisting of a large number of qubits capable of qubit gate
operation and state measurement.
[For what / why necessary?]
・Quantum computers are assumed to be much more powerful thanpresent computers in solving certain class of problems by
deploying quantum mechanical resources to computation.
Superconducting quantum computers are considered to be one of
the most promising candidates for quantum computers because of
their high degree of freedom in design and integration.
[International trends]
・In 2019, Google demonstrated quantum supremacy in a sample
containing 53 qubits 26. Thus, research and development of NISQ
27
(NoisyIntermediate-Scale
Quantum
computer),asuperconducting quantum computer consisting of several tens ofqubits without error correction, is actively conducted. In Japan,
the Q-LEAP Flagship project 28 and the Moonshot Research andDevelopment program 29 are conducting research and development.

[Requirements that may be required]・Research and development of qubits with long coherence time isnecessary. In addition, microwave transmission technology withlow reflection and loss, high-precision microwave pulse generation
technology, high-sensitivity microwave measurement technology,
and high-speed signal processing technology are required forhigh-speed and high-precision qubit gate operation, qubit
measurement, and quantum feedback. Furthermore, it is necessary
to increase the cooling power of dilution refrigerators and to
improve the reproducibility of superconducting quantum circuit
fabrication technology.

26

https://www.nature.com/articles/s41586-019-1666-5

27

https://doi.org/10.22331/q-2018-08-06-79

28

https://www.jst.go.jp/stpp/q-leap/

29

https://www.jst.go.jp/moonshot/program/goal6/index.html

52

Figure 26 ： Superconducting quantum computer

53

Chapter 5 : R&D Roadmap
・For the elemental technologies in Chapter 4, we have compiled aroadmap for the period from 2020 to 2035. The roadmap for
research and development of terrestrial and satellite quantum key
distribution (QKD) networks is as follows.

Figure 27 ： R&D Roadmap for QKD network

・The roadmap for research and development of quantum networks
is as follows.

54

Figure 28 ： R&D Roadmap for quantum network

55

Chapter 6 : Promotion Strategy
1. Overview
・ Promotion strategy that will be necessary for NICT to develop
QKD networks and quantum networks in society in cooperation
with external stakeholders.
・In order to deploy quantum networks in society, it is necessary to
promote five initiatives in an integrated manner: (1) research anddevelopment,(2)social
implementation,(3)international
collaboration, (4)system design, and (5)human resource
development.

Figure 29 : Promotion strategy for development of quantum
networks to society (overview)
2. Individual Promotion Strategy(1) Research and development● Promotion of continuous R&D at NICT・ Based on national plans and strategies as well as NICT's Fifth
Medium-to-Long-Term Plan , NICT will work on R&D of quantum
network technologies and securing related patents. In fields
56where it will take five to ten years to achieve research results, wewill promote the significance of the research and its results toobtain continuous investment.
● Promotion of technology transfer of research results at NICT・It is necessary for NICT to promote research and development forcompanies to catch up with the technology in cooperation with thegovernment and other organizations. It is also necessary tooperate and improve the system for smoother technology transferof the basic research results at NICT.
● Promotion of R&D through national projects
・ In technology fields where the market size is unclear and it isdifficult for companies to participate, such as quantum network
technology for which R&D is being promoted mainly in Europe andthe United States, it is necessary to promote R&D by establishinga collaboration system among industry, academia, and government
through national projects.
(2) Social implementation● Testbed establishment
・ NICT will establish an open testbed that connects quantum
technology innovation hubs in cooperation with the government,
companies, etc., upgrading the Tokyo QKD Testbed (see Initiatives
for Building quantum technology Platforms (p61).
・ Through the testbed, NICT will combine the achievements ofnational projects led by government to consolidate and effectively
utilize resources in Japan, and establish a framework for joint use
among industry, academia, and government.
● Provisionofapplication
development
infrastructure(establishment of business ecosystem)
・NICT will collaborate with governments, companies, the Quantum
ICT Forum, and others to provide opportunities to examine anddemonstrate new services and use cases at various layers,
strengthen application development, and examine businessecosystem models.
57

● Fostering industry
・ NICT will accelerate the diffusion and deployment of quantum
networks by promoting R&D and social implementation of quantum
networks by telecommunications carriers and service providers.
・To be able to manufacture major devices and parts on quantum
networks in Japan, NICT will actively collaborate with relatedcompanies such as vendors and component manufacturers inJapan, support the creation of parts manufacturing and businessmodels, and promote the establishment of supply chains. We will
also consider the creation of start-up companies from Sony.
(3) International cooperation● Collaboration with universities and research institutions
・ Considering international R&D trends on various quantum
technologies, such as ion trap and superconductivity, NICT will
collaborate with domestic and oversea research institutes and will
also consider applications of the research achievements on
quantum communications.
・Toward the realization of quantum networks, NICT will promotecollaboration with other universities and research institutions inorder to strengthen R&D of quantum relay technology, networkarchitecture, software, etc.
●Forming research community
・ NICT will promote the acquisition of research funds byparticipating in national projects such as the Moonshot Researchand Development Program, Q-LEAP, etc., and will also promote theformation of research communities in which participants ofnational projects and researchers from universities and research
institutions participate.
●Forming and supporting consortiums
・ NICT will promote collaboration among companies anduniversities through the Quantum ICT Forum.
・A consortium of quantum technology and Internet researchers
from industry, academia, and public research institute has been58

formed to promote quantum networks, and NICT will participate inand support such an interdisciplinary community.
● Organizing global partner network
・ NICT will accelerate the R&D of quantum networks while taking
into account the fact that quantum technology is closely related
to international cooperation and national security. At the sametime, NICT will actively promote the organization of global
strategic partners and supporters for standardization in order tobuild an international testbed.
● Launch of collaboration program with foreign institutions
・ NICT will promote discussions on the direction of future R&D
and international collaboration, utilizing the framework ofcollaboration with the EU and NSF.. NICT will strive to makeJapanese technology available worldwide while the human andfinancial resources for R&D on quantum technology are limited.
(4) System design● Promotion of international standardization
・ NICT, in cooperation with governments and companies, will
promote international standardization at the International
Telecommunication Union Telecommunication Standardization
Sector (ITU-T) andtheInternational
Organization
forStandardization / International Electrotechnical Commission(ISO/IEC JTC1), for the global spread of quantum network
technologies (especially QKD network technologies).
● Development of evaluation, certification and its framework
・ NICT, in cooperation with the government, companies, theQuantum ICT Forum, etc., will promote the development ofappropriate security assessment methods for QKD devices, thedocumentation of security requirements （ so-called Protection
Profiles (PPs) ） in compliance with international standards
developed by ISO/IEC, etc., and the development of an operation
framework for PPs.
59

● Application to cyber insurance
・ NICT, in cooperation with companies, etc., will consider theapplication of insurances and reduction of premiums for the
introduction of QKD.
(5) Human resource development● Developing and securing quantum natives
・NICT will develop “quantum natives” through the NICT QuantumCamp (NQC) program, started from 2020, in collaboration withgovernments, universities, companies, etc. NICT will also consider
developing human resources who can think in the full stack suchas quantum algorithms, high-level programming languages,architecture, etc., as well as human resources who can design theentire system.
・NICT will continue to secure human resources for research byaccepting student and adult interns at NICT, expanding
collaboration with universities, and developing attractive career
paths.
● Developing and securing diverse quantum human resources
・NICT will secure human resources with various skills not only inresearch but also in technology, intellectual property management,
accounting, etc., in order to strengthen NICT as a researchorganization.
● Utilization of NICT Quantum Security Hub
・ NICT will conduct human resource development and holdseminars utilizing the co-creation space at NICT’s new building as
the quantum security hub. NICT will also promote practical humanresource development programs utilizing open testbed connecting
various quantum research hubs.

60

Figure 30 ： Initiatives for building quantum technology platforms

61

Chapter 7 : Conclusion
・This white paper summarizes the image of society, use cases,
elemental technologies R&D roadmap from 2021 to 2035 andpromotion strategy on quantum networkｓ.
・ With regard to quantum networks, efforts for social
implementation of QKD and research and development for the“Quantum Internet” are being internationally promoted. In the
future, in accordance with the Fifth Medium-to-Long-Term Planof NICT and based on the promotion strategy of this white paper,
NICT will collaborate with experts, companies, universities, andresearch institutions in Japan and overseas to promote quantum
networks into society.
・In addition, NICT will update on this white paper based on futureinternational trends and R&D progresses.

Reference(1) Work member list (NICT)
Hitoshi Asaeda, Akie Izumi, Yasuki Ishitani, Shinji Ide, Tetsuya Ido,
Toshiyuki Ihara, Hiroyuki Endo, Nozomu Otsubo, Atsushi Kanno,
Yoshihiko Saito, Akihiko Sasaki, Masahide Sasaki, Shiho Shono,
Norihiko Sekine, Koichi Senba, Masahiro Takeoka, Yoshiro
Tsujimoto, Hirotaka Terai, Morio Toyoshima, Nils Nemitz, Hidekazu
Hachisu, Kazuhiro Hayasaka, Kentaro Furusawa, Shigeto Miki,
Takaya Miyazawa, Kazuhisa Matsuzono, Isao Morohashi, Kotaro
Yanagisawa, Yuya Yamaguchi, Fumiki Yoshihara(2) Update History- Release 0.9: April 30, 2021
The English text (version 0.9) was translated from the Japanese
text (version 1.0) by whitepaper work members using TexTra*, amachine translation system developed by NICT.
* https://mt-auto-minhon-mlt.ucri.jgn-x.jp/

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Quantum Network White Paper
Published March 2021
ISBN978-4-904020-14-2
National Institute of Information and Communications
Technology------------------------------4-2-1 Nukuikitamachi, Koganei City, Tokyo, 184-8795
E-mailnict-idi-wp@ml.nict.go.jp
URL https://www2.nict.go.jp/idi/
Unauthorized copying and replication of the contents of this paper
are prohibited.
-------------------------------

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