Improvement of two-way continuous-variable quantum key distribution using optical amplifiers

Abstract

The imperfections of a receiver's detector affect the performance of twoway continuous-variable quantum key distribution protocols and are difficult to adjust in practical situations. We propose a method to improve the performance of twoway continuous-variable quantum key distribution by adding a parameter-adjustable optical amplifier at the receiver. A security analysis is derived against a two-mode collective entangling cloner attack. Our simulations show that the proposed method can improve the performance of protocols as long as the inherent noise of the amplifier is lower than a critical value, defined as the tolerable amplifier noise. Furthermore, the optimal performance can approach the scenario where a perfect detector is used.

Entangled-Pair Transmission Improvement Using Distributed Phase-Sensitive Amplification

“…In addition, optical parametric amplification has been considered for quantum cloning [11] and for the manipulation [12,13] of continuous-variable (CV) quantum states [14]. Other recent work suggests that OPSAs can be used as preamplifiers in CV quantum key distribution systems to increase detection efficiency [15][16][17].…”

Security-proof framework for two-way Gaussian quantum-key-distribution protocols

“…[19,26,27] special attack parameters κ S , κ f or κ S , K f to be measured perfectly, and using those parameters we can bound Eve's information gain per mode using χ E (κ S , κ f ) or χ E (κ S , K f ) in Eq. (25). With that result in hand we can get a lower bound on Alice and Bob's SKE once we have evaluated their Shannon information in bits/symbol.…”

“…That said, decoy-state BB84 and conventional CV-QKD have the advantage of being one-way (OW) protocols, whereas FL-QKD is a two-way (TW) protocol, so that the former have much stronger security guarantees-e.g., decoy-state BB84 has coherent-attack security with finite-key analysis-while the latter's security to date is only against the frequencydomain collective attack in the asymptotic regime [14]. On the other hand, unlike other TW-QKD protocols [21][22][23][24][25][26][27][28][29], FL-QKD uses an optical amplifier in Bob's terminal to overcome the Bob-to-Alice channel's loss, making FL-QKD's channel loss equivalent to that of OW-QKD protocols.…”

“…The limited nature of FL-QKD's security proof is characteristic of the situation for other TW-QKD protocol's [14][15][16][17][21][22][23][24][25][26][27][28][29]. In part, this is because proof techniques for OW-QKD [30][31][32][33][34] do not readily cope with simultaneous attacks on both the Alice-to-Bob and Bob-to-Alice channels of a TW-QKD protocol.…”

Noiseless Linear Amplifiers in Entanglement-Based Continuous-Variable Quantum Key Distribution

“…The Gaussian-modulated CV-QKD protocols based on coherent states [7][8][9] have been experimentally demonstrated [6,[10][11][12] and have been shown to be secure against arbitrary attacks in the asymptotic [13] and finite-size regimes [14]. Two-way protocols [15][16][17][18] and thermal-state protocols [19][20][21] have been also designed.However, there still exists a gap between the theoretical security analyses and the practical implementations. Such real-life implementations of CV-QKD systems may contain overlooked imperfections, which might not have been accounted for in the theoretical security proofs, and may provide security loopholes.…”