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Continuous Variable Quantum Communications

Periodic Reporting for period 2 - CiViQ (Continuous Variable Quantum Communications)

Reporting period: 2020-04-01 to 2022-03-31

With the continuous growth of data traffic and potential disruptive hacking, cybersecurity and cryptography are of utmost importance. Classical cryptography can be vulnerable to undetected eavesdropping and to “store now-attack later” threats, especially considering the advent of quantum computers. By combining physical layer technologies and quantum information, quantum cryptography – primarily quantum key distribution (QKD) - offers the possibility to generate an encryption key with information theoretic security (ITS).
CiViQ project aims at opening a radically novel avenue towards flexible and cost-effective integration of quantum communication technologies, in particular Continuous-Variable Quantum Key Distribution (CV-QKD) systems, into emerging optical telecommunication networks.
The CiViQ specific objectives are summarized in:
• Top-down approach for specifications, defined by end users, services providers and system developers, of QKD systems available in current and future network infrastructures.
• Development of high performance CV-QKD systems and key components. The CV technology is ideally positioned to address co-existence with standard coherent optical communication, miniaturization and scalability. Because it uses classical modulation and detection techniques which do not require photon counting.
• Validation and benchmarking of CV-QKD systems for end-users. This includes the demonstration of end-to-end security services applied to use cases with stringent requirements in terms of security.
• Next-generation systems and networks, including CV-based quantum repeaters and measurement-device-independent (MDI) QKD, and interfaces to both ground-to-satellite and quantum repeaters.
CiViQ has advanced the CV-QKD technology on several fronts:
Use-cases and networks: We identified key applications, with respect to network protection layer (data, control and management), topology (point-to-point, point-to-multipoint, any-to-any) and/or domains (access, metro...). The top-down approach led to a technical development plan with application-specific systems: (i) class A, high TRL systems developed in CiViQ and to be deployed outside the lab by the end of the project (e.g. in OpenQKD testbeds); (ii) class B, low TRL systems using the most advanced technology, whose development will go beyond the project to reach field deployment.
Systems and components: We demonstrated a complete transmitter for the Open Development Platform, with interfaces for integration with SDN software stack and QRNG, high rate quantum communication in the Gbaud regime, on-chip detectors with a ‘bulk’ transmitter in a transmitted local oscillator CV-QKD scheme. At component level, the interfacing with signal processing electronics of a class A system was completed. Integrated QRNGs operational for CV-QKD were made available. A new generation of Photonic Integrated Circuits (PICs) for receiver, transmitter and QRNG components was developed.
Post processing, security analysis and advanced protocols: We have developed multi-edge-type low-density parity-check error correction codes and machine learning assisted carrier recovery, making systems robust against changing conditions. Critical advances have been made in the project on the security front: a security proof for discretely-modulated CV-QKD over noisy channels, counter-measures against Trojan horse attacks on the transmitter, a generalized security analysis framework for practical CV-QKD systems and noise suppression methods for multimode CV-QKD. Furthermore, we advanced towards asymptotic and finite size security proofs for more robust CV-MDI-QKD protocols.
Network and system integration: development of an SDN-based QKD network architecture allowing for the integration of quantum and classical communications in the same infrastructure, and produced the first version of the Software Stack. This stack is entirely model oriented and based on open interfaces and standards developed within ETSI.
Benchmarking, demonstration and standardization: We set plans for system and network demonstrations in the lab and in the field. Significantly, CiViQ technology has been demonstrated at several OpenQKD sites, e.g. Madrid, Barcelona and Copenhagen. We also introduced a specification/data sheet for device characterization, a necessary tool for standards, benchmarking and validation. CiViQ has been very active in several standardization activities, promoted by ETSI, ITU-T Y.3800 Y 3801, FG-QIT4N, QIRG-IETF, GSMA QC, IEEE P1913 and CEN/CENELEC FG/QT. Finally, CiViQ partners are main players within ETSI and the German BSI effort to establish certification for QKD.
Dissemination and exploitation: Highlights include: about 110 media pieces, with an estimated audience of 20 M, 122 posts on social media, with more than 200 K impressions, presence at numerous events, including MWC 2019 & 2022. 89 papers in refereed scientific journals, >200 conference presentations (about half of which invited) and 12 patent applications. Remarkably, some partners licensed their technology, this also leading to the creation of 3 spin-offs/start-ups (Luxquanta, Keequant and Alea Quantum Technologies).
After 42 months, the project has achieved results beyond the state-of-the-art in several activities, from fundamental concepts of security to new QKD schemes, devices, systems, signal post-processing and integration into telecommunications networks. Innovations include:
• Introduction of QKD network design optimization method for different application scenarios, including traditional solutions creating tree-like topologies.
• First implementation of the SDN QKD network stack, allowing a converged quantum-classical telecommunications infrastructure.
• Development of high-speed CV-QKD system, allowing for precise noise estimation in the LLO regime and suitable DSP algorithms.
• Demonstration of LLO CV-QKD with off-the-shelf components in WDM environment.
• Demonstration a record precision in excess noise measurement: 0.15 mSNU at receiver side.
• New integration techniques for combining InP and SiNx based components and first prototype of a PIC based CV-QKD transmitter.
• Study of new practical quantum side channels attacks and development of efficient counter-measures.
• New algorithms both for carrier recovery and for error correction codes.
• Establishment of a novel protocol, based on coherent phase masking, enabling covert CV-QKD in realistic WDM environment.
• Improved CV MDI-QKD protocol.
• A more compact squeezed light source and squeezed light transmitted through a fiber and measured with a local-local oscillator.
CiViQ will contribute developing a full-scale European Ecosystem on Quantum Secure Communication technologies. The project involves stakeholders from the full range of the value chain including Service providers (major European Telecommunication operators), System and Component developers (from both large Industry and SMEs) and Research Institutions/Universities, with expertise ranging from quantum technologies to system integration and network management. There have been tight collaborations between partners of CIVIQ and other QF projects, including QRANGE, QIA and UNIQORN. CIVIQ has also a leading role in future projects (Quantum Flagship FPA QSNP and EuroQCI-DEP1/2/3). The 3 related spin-offs/start-ups will be crucial technology contributors in establishing the European sovereignty in the critical field of quantum-safe communication.
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