发表机构
QuIIN - Quantum Industrial Innovation; Centro de Competência EMBRAPII CIMATEC; SENAI CIMATEC（QuIIN——量子工业创新中心; EMBRAPII CIMATEC 竞争力中心; 巴西国家工业培训服务中心CIMATEC中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一种基于带噪声相干态和位移接收机的CV-QKD协议，开发了参数估计策略，分析了安全性，并证明位移接收机在实验相关区域优于零差检测。
AI 中文摘要
通过执行位移操作后进行光子检测，可以实现接近最优的二元相干态判别。该位移作为一个控制参数，可被调优以优化选定的品质因数，这使得此类接收机在状态判别之外也具有吸引力。在此，我们将这种判别策略转化为一个完整的连续变量量子密钥分发（CV-QKD）协议，该协议基于带噪声相干态（位移热态）的二元字母表和位移接收机。由于标准的基于正交分量的方法不适用，我们开发了一种使用相同位移接收机来估计信道参数的策略。虽然使用开关检测可以获得密钥映射，但我们证明，可靠的参数估计需要具有足够分辨率的光子数分辨检测。有限的检测器分辨率会低估观测到的噪声，并构成潜在的安全漏洞，我们对此进行了量化，并表明可以通过适度的分辨率来缓解。我们分析了该协议在渐近区域内针对纠缠克隆集体攻击的安全性，涵盖直接协商和反向协商两种情况，并表明即使在噪声态制备和不完美检测条件下，该协议也能生成安全密钥。有趣的是，我们发现使判别错误概率最小化的位移在密钥生成方面也表现良好，从而为CV-QKD接收机提供了一种有用且解析上易处理的调优策略。我们评估了该协议在一系列透射率和噪声参数下的性能，表明位移接收机在实验相关区域内可以优于传统的零差检测。综合来看，我们的结果指出位移接收机是CV-QKD实现的一个有前景的替代方案。
英文摘要
Near-optimal binary coherent state discrimination can be achieved by performing a displacement operation followed by photon detection. This displacement serves as a control parameter that can be tuned to optimize a chosen figure of merit, which makes such receivers attractive beyond state discrimination. Here, we turn this discrimination strategy into a complete continuous-variable quantum key distribution (CV-QKD) protocol based on a binary alphabet of noisy coherent states (displaced thermal states) and displacement receivers. We develop a strategy for estimating the channel parameters with the same displacement receiver, since standard quadrature-based methods do not apply. While a key map can be obtained with on/off detection, we demonstrate that reliable parameter estimation requires photon-number-resolving detection with sufficient resolution. Finite detector resolution underestimates the observed noise and constitutes a potential security loophole, which we quantify and show to be mitigable with modest resolution. We analyze the protocol's security against entangling-cloner collective attacks in the asymptotic regime, for both direct and reverse reconciliation, and show that it can generate secret keys even under noisy state preparation and imperfect detection. Interestingly, we find that the displacement that minimizes the discrimination error probability also performs well for key generation, thus providing a useful and analytically tractable tuning strategy for the CV-QKD receiver. We evaluate the protocol's performance over a range of transmittances and noise parameters, showing that the displacement receiver can outperform conventional homodyne detection in experimentally relevant regimes. Together, our results point to displacement receivers as a promising alternative for CV-QKD implementations.
