One-Time Shot-Noise Unit Calibration Method for Continuous-Variable Quantum Key Distribution

Abstract

The shot-noise unit in continuous-variable quantum key distribution plays an important and fundamental role in experimental implementation as it is used as a normalization parameter that contribute to perform security analysis and distill the key information. However, the traditional calibration procedure and detector model can not cover all system noise in practical application, which will result in some loopholes and influence the practical security. What's more, the traditional procedure is also rather complicated and has difficulty in compatible with automatic operating system. In this paper we propose a calibration model based on the proposed trusted detector model, which could naturally close the loopholes in practical application. It can help identify the shot-noise unit in only one step, which can not only effectively simplify the evaluation process but also reduce the statistical fluctuation, while two steps are needed in traditional method. We prove its feasibility and derive the complete version of the corresponding entanglement-based model. Detailed security analysis against arbitrary collective attacks and numerous simulation results in both the asymptotic limit regime and the finite-size regime are provided. A proof-of-principle experiment has been implemented and the results indicate that the one-time-calibration model can be employed as a powerful substitution to calibrate the shot-noise unit. Our method paves the way for the deployment of continuous-variable quantum key distribution with real time calibration and automatic operation.

Long-Distance Continuous-Variable Quantum Key Distribution over 202.81 km of Fiber

“…A phase modulator (PM 2 , EOSPACE, PM-5K4-10-PFA-PFA-UV) on the LO path selects the signal quadrature components randomly. The signal path is randomly switched off to do the real time shot-noise unit calibration [23]. The signal pulses interfere with the LO pulses on a self-developed shot-noise-limited balanced pulsed homodyne detector whose output is proportional to the signal and LO intensity.…”

“…Note, the scheme with the transmitted LO may open loopholes for the eavesdropper to intercept the secret keys by manipulating the intensity of LO pulses [25,26]. To prevent such side-channel attacks, in the experiment, the photodiode for the synchronization is also used for the LO monitoring and we will randomly switch off the signal pulses to do the real time shot-noise unit cal-ibration [23]. Thus, the system is immune to most current side-channel attacks against LO.…”

A modified practical homodyne detector model for continuous-variable quantum key distribution: detailed security analysis and improvement by the phase-sensitive amplifier

“…Thus, we focus on the relation of the electronic noise of the two models. As is analyzed in [28], the electronic noise η e in the modified practical homodyne detector model is defined as…”

“…The relation between the modified practical homodyne detector model and the conventional practical homodyne detector model is studied in detail, while we show that the modified practical homodyne detector model can describe the practical PM model. The one-time-calibration method [28] can be viewed as a particular instance that directly benefits from the modified practical homodyne detector model. We further improve the modified practical homodyne detector model by applying the phase-sensitive amplifier (PSA).…”

Unidimensional Continuous-Variable Quantum Key Distribution with Untrusted Detection under Realistic Conditions

“…Both DV and CV systems can be integrated on chip [ 12 , 13 , 14 , 15 , 16 ] and operate at room temperature, but CV systems have significant advantages to achieve higher rate in a short distance link [ 17 ]. Thus, the CV-QKD protocols have attracted much attention in the past few years [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. To meet a variety of application needs, much theoretical and experimental research of CV-QKD was done [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ].…”