The imperfections of a receiver's detector affect the performance of two-way continuous-variable quantum key distribution protocols and are difficult to adjust in practical situations. We propose a method to improve the performance of two-way 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.
@article{arxiv.1307.7590,
title = {Improvement of two-way continuous-variable quantum key distribution using optical amplifiers},
author = {Yi-Chen Zhang and Zhengyu Li and Christian Weedbrook and Song Yu and Wanyi Gu and Maozhu Sun and Xiang Peng and Hong Guo},
journal= {arXiv preprint arXiv:1307.7590},
year = {2014}
}