Detection of quantum circular QAM signals

In this paper we consider the quantum detection problem with M-ary quadrature amplitude modulation (QAM) pure states. We apply the square root measurement (SRM) for detection, which is optimum for phase shift keying modulation in terms of error probability, to the circular QAM. From our simulations we show that the circular QAM can provide the better performance than rectangular QAM in quantum detection.