Quasi-optimum Quantum Receiver for Binary Squeezed-state Signal

Construction method of an optical receiver is proposed for binary squeezed state signal, which has substantially lower noise properties than a conventional coherent state signal. The receiver can extract most of the performance of a squeezed light. Condition of optimum degree of squeezing are given to the proposed receivers for a binary phase-shift-keyed (BPSK) and an amplitude shift keyed (ASK) signals, respectively. It is also shown that the concept of this receiver can be applied for signals in any other quantum state which is generated from a coherent state by a unitary transformation.