Phase noise model for continuous-variable quantum key distribution using a local local oscillator

Yun Shao, Heng Wang, Yaodi Pi, Wei Huang, Yang Li, Jinlu Liu, Jie Yang, Yichen Zhang, and Bingjie Xu
Phys. Rev. A 104, 032608 – Published 14 September 2021

Abstract

The value of residual phase noise, after phase compensation, is one of the key limitations of performance improvement for continuous-variable quantum key distribution using a local local oscillator (LLO CV-QKD) system, since it is the major excess noise. However, due to the nonideality of the realistic devices implemented in practice, for example, imperfect lasers, detectors, and unbalanced interferometers, the value of residual phase noise in the current system is still relatively large. Here, we develop a phase noise model to improve the phase noise tolerance of the LLO CV-QKD schemes. In our model, part of the phase-reference measurement noise associated with detection efficiency and electronic noise of Bob's detector as well as a real-time monitored phase-reference intensity at Bob's side is considered trusted because it can be locally calibrated by Bob. We show that using our phase noise model can significantly improve the secure key rate and transmission distance of the LLO CV-QKD system. We further conduct an experiment to substantiate the superiority of the phase noise model. Based on experimental data of a LLO CV-QKD system in the 25-km optical fiber channel, we demonstrate that the secure key rate under our phase noise model is approximately 40% higher than that under the conventional phase noise model.

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  • Received 3 February 2021
  • Revised 30 April 2021
  • Accepted 27 August 2021

DOI:https://doi.org/10.1103/PhysRevA.104.032608

©2021 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
Quantum Information, Science & Technology

Authors & Affiliations

Yun Shao1, Heng Wang1, Yaodi Pi1, Wei Huang1, Yang Li1, Jinlu Liu1, Jie Yang1, Yichen Zhang2, and Bingjie Xu1,*

  • 1Science and Technology on Communication Security Laboratory, Institute of Southwestern Communication, Chengdu 610041, China
  • 2State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China

  • *xbjpku@pku.edu.cn

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Vol. 104, Iss. 3 — September 2021

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