编程肯尼迪接收机以实现容量最大化与最小化一次性错误概率

Sub-shot-noise-limited fiber-optic quantum receiver

We experimentally demonstrate a quantum receiver based on Kennedy scheme for discrimination between two phase-modulated weak coherent states. The receiver is assembled entirely from the standard fiber-optic elements and operates at the conventional telecom wavelength 1.55 microns. The local oscillator and the signal are transmitted through different optical fibers, and the displaced signal is measured with a high-efficiency superconducting nanowire single-photon detector. We show the discrimination error rate two times below the shot-noise limit.

Reinforcement-learning calibration of coherent-state receivers on variable-loss optical channels

We study the problem of calibrating a quantum receiver for optical coherent states when transmitted on a quantum optical channel with variable transmissivity, a common model for long-distance optical-fiber and free/deep-space optical communication. We optimize the error probability of legacy adaptive receivers, such as Kennedy's and Dolinar's, on average with respect to the channel transmissivity distribution. We then compare our results with the ultimate error probability attainable by a general quantum device, computing the Helstrom bound for mixtures of coherent-state hypotheses, for the fi…

Demonstration of near-Optimal Discrimination of Optical Coherent States

The optimal discrimination of non-orthogonal quantum states with minimum error probability is a fundamental task in quantum measurement theory as well as an important primitive in optical communication. In this work, we propose and experimentally realize a new and simple quantum measurement strategy capable of discriminating two coherent states with smaller error probabilities than can be obtained using the standard measurement devices; the Kennedy receiver and the homodyne receiver.

Distinguishing between optical coherent states with imperfect detection

Several proposed techniques for distinguishing between optical coherent states are analyzed under a physically realistic model of photodetection. Quantum error probabilities are derived for the Kennedy receiver, the Dolinar receiver and the unitary rotation scheme proposed by Sasaki and Hirota for sub-unity detector efficiency. Monte carlo simulations are performed to assess the effects of detector dark counts, dead time, signal processing bandwidth and phase noise in the communication channel. The feedback strategy employed by the Dolinar receiver is found to achieve the Helstrom bound for su…

利用位移、反压缩和光子数分辨检测近最优区分位移压缩二进制信号

Near-optimal discrimination of displaced squeezed binary signals using displacement, inverse-squeezing, and photon-number-resolving detection

本文提出反压缩Kennedy接收器，用于区分二进制相位调制位移压缩真空态，通过反压缩增强光子数对比度，实现超越标准量子限和Helstrom界，且在实际参数下保持鲁棒性。

Real-time phase-reference monitoring of a quasi-optimal coherent-state receiver

The Kennedy-like receiver is a quasi-optimal receiver employed in binary phase-shift-keyed communication schemes with coherent states. It is based on the interference of the two signals encoding the message with a reference local oscillator and on/off photodetection. We show both theoretically and experimentally that it is possible to extract useful information about the phase reference by Bayesian processing of the very same data sample used to discriminate the signals shot by shot. We demonstrate that the minimum uncertainty in phase estimation, given by the inverse of the Fisher information…

基于关联-位移转换的微波量子照明

Microwave quantum illumination with correlation-to-displacement conversion

本文扩展微波量子照明的关联-位移转换模块以容纳实验缺陷，提出返回信号放大，并结合 Kennedy 接收器与光子数分辨检测分析理想及噪声条件下的量子检测优势。