Multi-User Detection Based on Quantum Square-Root Measurement

The quantum multi-user detection technique with quantum detection under quantum multiple-access channel is a promising field in communications, it has promised an efficient solution to the NP hard problem in conventional optimal solution of multi-user detection. In this paper, a solution of multi-user detection in multi-access quantum channel based on the quantum square-root measurement is proposed, by which the minimum square-root probability of error can be gathered, and the probability of symbol error under various correlation coefficients with OOK and PSK modulation is evaluated. Compared with OOK modulation, the performance of PSK modulation can be improved greatly, but with high computation complexity. Then, a threshold algorithm and a new quantum square-root measurement formula are developed to reduce the computation complexity. The numerical experiments show that these methods can lower the complexity greatly.