We consider the phase sensing via weak optical coherent state at quantum limit precision. A new detection scheme for the phase estimation is proposed which is inspired by the suboptimal quantum measurement in coherent optical communication. We theoretically analyze a performance of our detection scheme, which we call the displaced-photon counting, for phase sensing in terms of the Fisher information and show that the displaced-photon counting outperforms the static homodyne and heterodyne detections in wide range of the target phase. The proof-of-principle experiment is performed with linear optics and a superconducting nanowire single photon detector. The result shows that our scheme overcomes the limit of the ideal homodyne measurement even under practical imperfections.
@article{arxiv.1604.04319,
title = {Optical phase estimation via coherent state and displaced photon counting},
author = {Shuro Izumi and Masahiro Takeoka and Kentaro Wakui and Mikio Fujiwara and Kazuhiro Ema and Masahide Sasaki},
journal= {arXiv preprint arXiv:1604.04319},
year = {2016}
}