Demonstration of optimal non-projective measurement of binary coherent states with photon counting
Demonstration of optimal non-projective measurement of binary coherent states with photon counting
复制标题
DOI：
10.1038/s41534-022-00595-3
复制
发表时间：
2022-07
影响因子：
7.6
通讯作者：
M. Dimario;F. Becerra
中科院分区：
文献类型：
--
作者：
M. Dimario;F. Becerra
量子态鉴别是量子测量理论中的一个核心问题，其应用范围从量子通信到量子计算。用于状态鉴别的典型测量范例涉及最小错误概率或具有最小不确定结果概率的明确鉴别。或者，一个最佳的非决定性测量，一个非投影测量，实现最小的误差为一个给定的非决定性的概率。这种更一般的测量包含了用于状态鉴别的标准测量范例，并为量子信息和通信提供了更强大的工具。在这里，我们实验证明了最佳的非决定性测量的歧视二元相干态使用线性光学和单光子探测。我们的演示使用基于干涉，单光子探测和快速反馈的相干位移操作，为高保真度的最佳非投影量子测量准备最佳反馈策略。这种广义测量使我们能够以最佳的方式从最小误差过渡到二进制相干态的明确测量。作为一个特殊的情况下，我们使用这个一般的测量来实现相位相干态的最佳最小误差测量，这是平均功率约束下的通信的最佳调制。此外，我们提出了一种混合测量，利用二进制最佳的非决定性的测量，结合顺序，明确的状态消除，实现更高维的相干态的非决定性的测量。
Quantum state discrimination is a central problem in quantum measurement theory, with applications spanning from quantum communication to computation. Typical measurement paradigms for state discrimination involve a minimum probability of error or unambiguous discrimination with a minimum probability of inconclusive results. Alternatively, an optimal inconclusive measurement, a non-projective measurement, achieves minimal error for a given inconclusive probability. This more general measurement encompasses the standard measurement paradigms for state discrimination and provides a much more powerful tool for quantum information and communication. Here, we experimentally demonstrate the optimal inconclusive measurement for the discrimination of binary coherent states using linear optics and single-photon detection. Our demonstration uses coherent displacement operations based on interference, single-photon detection, and fast feedback to prepare the optimal feedback policy for the optimal non-projective quantum measurement with high fidelity. This generalized measurement allows us to transition among standard measurement paradigms in an optimal way from minimum error to unambiguous measurements for binary coherent states. As a particular case, we use this general measurement to implement the optimal minimum error measurement for phase-coherent states, which is the optimal modulation for communications under the average power constraint. Moreover, we propose a hybrid measurement that leverages the binary optimal inconclusive measurement in conjunction with sequential, unambiguous state elimination to realize higher dimensional inconclusive measurements of coherent states.