Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Quantum Optics and Photon Counting

Characterizing background photons and dark counts in real field TF-QKD setup

Salvatore Virzì, Alice Meda, Cecilia Clivati, Simone Donadello, Carlo Liorni, Gianluca Bertaina, Marco Gramegna, Ivo Pietro Degiovanni, Massimiliano Dispenza, Marco Genovese, Davide Calonico

Published Jun 6, 2023• 0 citations
Publisher

Abstract

Quantum key distribution (QKD) allows the sharing of secret cryptographic keys between two distant users, whose intrinsic security is guaranteed by the laws of nature.Nowadays, the most promising technique for the integration of QKD in already deployed long-haul telecommunication fiber networks is the Twin-field QKD (TF-QKD) protocol, but it requires that the communication channel is stable in terms of phase oscillations and it is free from background light, that reduces the transmission key-rate.Recently, we presented a solution [1] to the phase stabilization problem, derived from atomic clocks comparison technology, demonstrating advantages in performances of real word TF-QKD.Here we quantify and characterize the background photons, analyzing in details their effects on the transmission and the practicalities to reduce their contribution to a negligible level.

DOI
10.1117/12.2669073

Related papers

Atomic Clocks Technologies for Twin-Field QKD in Real World

Cecilia Clivati, Alice Meda, Simone Donadello +10 more

Twin-field quantum key distribution on optical fibers, a promising approach to long-distance secure communication, can take advantage from atomic clocks technologies such as narrow linewidth lasers and phase-coherent distribution of optical pulses. We will describe the integration of these technologies in a TF-QKD setup implemented on an extended metropolitan fiber network and report on the expected QKD performances.

Optical Fiber Communication Conference•Mar 1, 2023•1 citation

QKD and frequency distribution cooperation: the Twin-field QKD case

Alice Meda, Cecilia Clivati, Salvatore Virzì +6 more

The integration of Quantum Key Distribution (QKD) protocols in metropolitan networks, exploiting already deployed telecommunication fibers, requires particular attention due to the non-ideal environment in which the protocol operates. At present, Twin-field QKD is one of the most promising techniques to reach the extension of QKD transmission but its real-word exploitation requires that the communication channel is stable in terms of optical length and is free from background light that increase the errors in the transmitted keys. Adapting interferometry techniques derived from frequency metrology, we recently proposed a solution [1] for a tight channel length control, and demonstrated it on a 206 km metropolitan fiber with 65 dB loss. Here we analyze in details the effects of background photons and the solutions that we applied to reduce their contribution to a negligible level.

IEEE Workshop on Low Temperature Electronics (WOLTE)•Jun 6, 2022•0 citations

Atomic Clocks Technologies for Twin-Field QKD in Real World

Cecilia Clivati, Alice Meda, Simone Donadello +10 more

Twin-field quantum key distribution on optical fibers, a promising approach to long-distance secure communication, can take advantage from atomic clocks technologies such as narrow linewidth lasers and phase-coherent distribution of optical pulses. We will describe the integration of these technologies in a TF-QKD setup implemented on an ex-tended metropolitan fiber network and report on the expected QKD performances.

Optical Fiber Communication Conference•Jan 1, 2023•0 citations

Secure Quantum Key Distribution over Long-Haul Optical Fibers Using Twin-Field QKD Protocol

Zebo Khudoyqulova, Khulkar Kasimova, Temur Eshchanov +3 more

Quantum Key Distribution (QKD) offers information-theoretic security, making it a cornerstone of future cryptographic infrastructures in the era of quantum computing. However, long-distance deployment of conventional QKD protocols is limited by channel losses, detector noise, and the fundamental repeaterless Pirandola-Laurenza-Ottaviani-Banchi (PLOB) bound. To address these challenges, this paper investigates the Twin-Field QKD (TF-QKD) protocol, which enables secure key exchange over long-haul optical fibers by exploiting single-photon interference at an untrusted intermediate node. An elaborate system model is provided with optical channel impairments, imperfections of detector and phase stabilization conditions. Finite-key analysis, error correction as well as privacy amplification are placed and made together in order to increase robustness of protocol against practical attacks. The simulation data show that TFQKD can reach secure key rates of over 500 km and is out of reach of decoy-state QKD but nearly close to fundamental limits. These results demonstrate that TF-QKD has the potential to practicalize quantumsecure communication at large scale and in a costeffective way, which can constitute a sub-unit of the future quantum internet.

Optical Communication, Photonics, Telecommunications, and Intelligent Machine Applications (OPTIMA)•Dec 4, 2025•0 citations

Coherent phase transfer for real-world twin-field quantum key distribution (Conference Presentation)

Salvatore Virzì, Cecilia Clivati, Alice Meda +6 more

Nowadays, a technological challenge is to integrate quantum key distribution (QKD) protocols in already present telecommunication fiber networks. Twin-field QKD is one of the most promising techniques on long distances, but requires stabilizing the optical length of the communication channels between parties. Adapting interferometry techniques derived from frequency metrology, we developed a solution for the simultaneous key sharing and channel length control, and we demonstrated it on a 206 km field-deployed fiber with 65 dB loss. Our method reduces the quantum-bit-error-rate contributed by channel length variations to <1%, representing an effective solution for real-world quantum communications.

Quantum Communications and Quantum Imaging•Oct 3, 2022•0 citations

Twin-Field Quantum Key Distribution without Phase Locking

Wei Li, Li‐Kang Zhang, Yichen Lu +11 more

Twin-field quantum key distribution (TF-QKD) has emerged as a promising solution for practical quantum communication over long-haul fiber. However, previous demonstrations on TF-QKD require the phase locking technique to coherently control the twin light fields, inevitably complicating the system with extra fiber channels and peripheral hardware. Here, we propose and demonstrate an approach to recover the single-photon interference pattern and realize TF-QKD without phase locking. Our approach separates the communication time into reference frames and quantum frames, where the reference frames serve as a flexible scheme for establishing the global phase reference. To do so, we develop a tailored algorithm based on fast Fourier transform to efficiently reconcile the phase reference via data postprocessing. We demonstrate no-phase-locking TF-QKD from short to long distances over standard optical fibers. At 50-km standard fiber, we produce a high secret key rate (SKR) of 1.27 Mbit/s, while at 504-km standard fiber, we obtain the repeaterlike key rate scaling with a SKR of 34 times higher than the repeaterless secret key capacity. Our work provides a scalable and practical solution to TF-QKD, thus representing an important step towards its wide applications.

arXiv:2212.04311•Physical Review Letters•Jun 20, 2023•56 citations
Quantum key distribution (QKD) allows the sharing of secret cryptographic keys between two distant users, whose intrinsic security is guaranteed by the laws of nature.Nowadays, the most promising technique for the integration of QKD in already deployed long-haul telecommunication fiber networks is the Twin-field QKD (TF-QKD) protocol, but it requires that the communication channel is stable in terms of phase oscillations and it is free from background light, that reduces the transmission key-rate.Recently, we presented a solution [1] to the phase stabilization problem, derived from atomic clocks comparison technology, demonstrating advantages in performances of real word TF-QKD.Here we quantify and characterize the background photons, analyzing in details their effects on the transmission and the practicalities to reduce their contribution to a negligible level.
The integration of Quantum Key Distribution (QKD) protocols in metropolitan networks, exploiting already deployed telecommunication fibers, requires particular attention due to the non-ideal environment in which the protocol operates. At present, Twin-field QKD is one of the most promising techniques to reach the extension of QKD transmission but its real-word exploitation requires that the communication channel is stable in terms of optical length and is free from background light that increase the errors in the transmitted keys. Adapting interferometry techniques derived from frequency metrology, we recently proposed a solution [1] for a tight channel length control, and demonstrated it on a 206 km metropolitan fiber with 65 dB loss. Here we analyze in details the effects of background photons and the solutions that we applied to reduce their contribution to a negligible level.
Quantum Key Distribution (QKD) offers information-theoretic security, making it a cornerstone of future cryptographic infrastructures in the era of quantum computing. However, long-distance deployment of conventional QKD protocols is limited by channel losses, detector noise, and the fundamental repeaterless Pirandola-Laurenza-Ottaviani-Banchi (PLOB) bound. To address these challenges, this paper investigates the Twin-Field QKD (TF-QKD) protocol, which enables secure key exchange over long-haul optical fibers by exploiting single-photon interference at an untrusted intermediate node. An elaborate system model is provided with optical channel impairments, imperfections of detector and phase stabilization conditions. Finite-key analysis, error correction as well as privacy amplification are placed and made together in order to increase robustness of protocol against practical attacks. The simulation data show that TFQKD can reach secure key rates of over 500 km and is out of reach of decoy-state QKD but nearly close to fundamental limits. These results demonstrate that TF-QKD has the potential to practicalize quantumsecure communication at large scale and in a costeffective way, which can constitute a sub-unit of the future quantum internet.
Nowadays, a technological challenge is to integrate quantum key distribution (QKD) protocols in already present telecommunication fiber networks. Twin-field QKD is one of the most promising techniques on long distances, but requires stabilizing the optical length of the communication channels between parties. Adapting interferometry techniques derived from frequency metrology, we developed a solution for the simultaneous key sharing and channel length control, and we demonstrated it on a 206 km field-deployed fiber with 65 dB loss. Our method reduces the quantum-bit-error-rate contributed by channel length variations to <1%, representing an effective solution for real-world quantum communications.
Twin-field quantum key distribution (TF-QKD) has emerged as a promising solution for practical quantum communication over long-haul fiber. However, previous demonstrations on TF-QKD require the phase locking technique to coherently control the twin light fields, inevitably complicating the system with extra fiber channels and peripheral hardware. Here, we propose and demonstrate an approach to recover the single-photon interference pattern and realize TF-QKD without phase locking. Our approach separates the communication time into reference frames and quantum frames, where the reference frames serve as a flexible scheme for establishing the global phase reference. To do so, we develop a tailored algorithm based on fast Fourier transform to efficiently reconcile the phase reference via data postprocessing. We demonstrate no-phase-locking TF-QKD from short to long distances over standard optical fibers. At 50-km standard fiber, we produce a high secret key rate (SKR) of 1.27 Mbit/s, while at 504-km standard fiber, we obtain the repeaterlike key rate scaling with a SKR of 34 times higher than the repeaterless secret key capacity. Our work provides a scalable and practical solution to TF-QKD, thus representing an important step towards its wide applications.