High key rate continuous-variable quantum key distribution with a real local oscillator

Abstract

Continuous-variable quantum key distribution (CVQKD) with a real local oscillator (LO) has been extensively studied recently due to its security and simplicity. In this paper, we propose a novel implementation of a high-key-rate CVQKD with a real LO. Particularly, with the help of the simultaneously generated reference pulse, the phase drift of the signal is tracked in real time and then compensated. By utilizing the time and polarization multiplexing techniques to isolate the reference pulse and controlling the intensity of it, not only the contamination from it is suppressed, but also a high accuracy of the phase compensation can be guaranteed. Besides, we employ homodyne detection on the signal to ensure the high quantum efficiency and heterodyne detection on the reference pulse to acquire the complete phase information of it. In order to suppress the excess noise, a theoretical noise model for our scheme is established. According to this model, the impact of the modulation variance and the intensity of the reference pulse are both analysed theoretically and then optimized according to the experimental data. By measuring the excess noise in the 25km optical fiber transmission system, a 3.14Mbps key rate in the asymptotic regime proves to be achievable. This work verifies the feasibility of the high-key-rate CVQKD with a real LO within the metropolitan area.

Continuous‐Variable Quantum Key Distribution with Gaussian Modulation—The Theory of Practical Implementations

“…By now, many experimental demonstrations underlined the feasibility of CV-QKD with coherent states. [14][15][16][17][18][19][20][21][22][23][24][25] The experimental performance of these works has to be evaluated in the context of the various settings and assumptions that the respective authors applied and are therefore difficult to compare. After all, a CV-QKD setup is primarily appraised by the secure-key rate that can be achieved over a given transmission distance.…”

“…[18][19][20]22,24,25,34] Some of the latest papers demonstrated the feasibility of a secure-key rate of a few Mbit s −1 over a channel length of some tens of kilometres using an LLO scheme. [24,25] A good overview of the state-of-the-art in GM CV-QKD and the security of various protocols is given in ref. [35]; however, that review does not provide any detailed calculations.…”

Quantum secret sharing using weak coherent states

“…After the quantum transmission stage, the n − 1 players and the dealer first correct the raw data by performing rotation x k = x k cos φ k − p k sin φ k ; p k = x k sin φ k + p k cos φ k , then they proceed with the remaining steps of the protocol. This phase recovery scheme has been successfully demonstrated in CV-QKD [32,39,41,42].…”

Unidimensional continuous-variable measurement-device-independent quantum key distribution

“…In theory, Gaussian-modulated coherent-state (GMCS) CV-QKD protocols have been proved to be secure under collective attacks [19,20] and coherent attacks [21,22], even with finite-size regime [23,24] and composable security [25] taken into full analysis. Numerous experimental realizations in the laboratory [26][27][28][29] and several field tests [30][31][32] have been achieved, which show the feasibility and practicability of CV-QKD protocols. A recent experiment of all-fiber GMCS CV-QKD has achieved the secure transmission distance beyond 100 km under laboratory conditions, which will contribute to the realization of metropolitan quantum networks with conventional telecom technologies [33].…”