Quantum Receiver for Binary Coherent-State Signals with Constant-Intensity Local Lasers

A quantum receiver capable of approaching the fundamental quantum limit on bit error probability is described and evaluated. Conventional optical and abstract quantum mechanical descriptions are provided and the underlying principles derived in both domains, thus providing a bridge to optimum quantum measurements in terms of well-understood optical communications concepts. Receiver performance is evaluated for the case of binary phase-shift keyed modulation, and it is shown that significant gains can be achieved over near optimum receivers reported previously in the literature. This new receiver concept can be implemented using practical measurements amenable to high data-rate operation, hence it may enable future deep-space optical communications with performance approaching the greatest possible fidelity allowed by the laws of quantum mechanics.