Zhong Hai, Wang Yijun, Wang Xudong, Liao Qin, Wu Xiaodong, Guo Ying
School of Information Science and Engineering, Central South University, Changsha 410083, China.
School of IOT Engineering, Taihu University, Wuxi 214064, China.
Entropy (Basel). 2018 Aug 6;20(8):578. doi: 10.3390/e20080578.
The scheme of the self-referenced continuous-variable quantum key distribution (SR CV-QKD) has been experimentally demonstrated. However, because of the finite dynamics of Alice's amplitude modulator, there will be an extra excess noise that is proportional to the amplitude of the reference pulse, while the maximal transmission distance of this scheme is positively correlated with the amplitude of the reference pulse. Therefore, there is a trade-off between the maximal transmission distance and the amplitude of the reference pulse. In this paper, we propose the scheme of SR CV-QKD with virtual photon subtraction, which not only has no need for the use of a high intensity reference pulse to improve the maximal transmission distance, but also has no demand of adding complex physical operations to the original self-referenced scheme. Compared to the original scheme, our simulation results show that a considerable extension of the maximal transmission distance can be obtained when using a weak reference pulse, especially for one-photon subtraction. We also find that our scheme is sensible with the detector's electronic noise at reception. A longer maximal transmission distance can be achieved for lower electronic noise. Moreover, our scheme has a better toleration of excess noise compared to the original self-referenced scheme, which implies the advantage of using virtual photon subtraction to increase the maximal tolerable excess noise for distant users. These results suggest that our scheme can make the SR CV-QKD from the laboratory possible for practical metropolitan area application.
自参考连续变量量子密钥分发（SR CV-QKD）方案已通过实验验证。然而，由于爱丽丝幅度调制器的动态范围有限，会存在与参考脉冲幅度成正比的额外过量噪声，而该方案的最大传输距离与参考脉冲幅度呈正相关。因此，在最大传输距离和参考脉冲幅度之间存在权衡。在本文中，我们提出了具有虚拟光子减法的SR CV-QKD方案，该方案不仅无需使用高强度参考脉冲来提高最大传输距离，而且也无需在原始自参考方案中添加复杂的物理操作。与原始方案相比，我们的模拟结果表明，使用弱参考脉冲时可以显著扩展最大传输距离，特别是对于单光子减法。我们还发现我们的方案对接收端探测器的电子噪声很敏感。电子噪声越低，可实现的最大传输距离就越长。此外，与原始自参考方案相比，我们的方案对过量噪声具有更好的容忍度，这意味着使用虚拟光子减法来增加远程用户可容忍的最大过量噪声的优势。这些结果表明，我们的方案可以使SR CV-QKD从实验室走向实际的城域应用成为可能。
