Scalable Implementation of Temporal and Phase Encoding QKD with Phase-Randomized States

Year: 2024

Authors: Francesconi S., De Lazzari C., Ribezzo D., Vagniluca I., Biagi N., Occhipinti T., Zavatta A., Bacco D.

Autors Affiliation: QTI Srl, I-50125 Florence, Italy; CNR INO, I-50125 Florence, Italy; Univ Napoli Federico II, Naples, Italy; Univ Florence, Dept Phys & Astron, I-50019 Sesto Fiorentino, Italy.

Abstract: Quantum key distribution (QKD), that is, exchanging cryptographic keys encoded in quantum particles exploiting the laws of quantum physics, is already a reality in our society. Current implementations are based on attenuated laser technique, a practical replacement of single photons which requires a random phase for each quantum state in order to achieve the highest level of security. In particular, the time-bin and phase encoding techniques are mainly exploiting laser in gain-switching modes combined with asymmetric interferometers or multiple laser sources in a master-slave configuration, which present limitations in terms of stability and scalability. In this work, a novel scheme for implementing a reconfigurable and scalable QKD transmitter based on the time-bin encoding protocol with a decoy-state method employing phase-randomized weak coherent states is proposed and demonstrated. The scheme is tested and validated up to 26 dB-attenuation channel using standard single-photon detectors working in the telecom wavelength range. Quantum key distribution (QKD), exchanging cryptographic keys exploiting the laws of quantum physics, is already a reality in our society. Current implementations are based on attenuated lasers, which present limitations in terms of stability and scalability. This work demonstrates a novel scheme for implementing a reconfigurable and scalable QKD transmitter based on time-bin encoding and decoy-state employing phase-randomized weak states.image

Journal/Review: ADVANCED QUANTUM TECHNOLOGIES

Volume: 7 (2)      Pages from:   to:

More Information: This work was funded by the European Union (ERC, QOMUNE, 101077917, by the Project EQUO (European QUan- tum ecOsystems) which is funded by the European Commis- sion in the Digital Europe Programme under the grant agreement No 101091561, the Project SERICS (PE00000014) un- der the MUR National Recovery and Resil ience Plan funded by the European Union – NextGenerationEU, the Project QuONTENT under the it Progetti di Ricerca, CNR program funded by the Consiglio Nazionale delle Ricerche (CNR) and by the European Union – PON Ricerca e Innovazione 2014- 2020 FESR – Project ARS01/00734 QUANCOM, the Project QUID (Quantum Italy Deployment) funded by the European Commission in the Digital Europe Programme under the grant agreement No 101091408.
KeyWords: phase randomization; quantum communication; quantum Key Distribution; quantum photonics; security of QKD
DOI: 10.1002/qute.202300224