Optical phase estimation via coherent state and displaced photon   counting
  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. 
Shuro Izumi, Masahiro Takeoka, Kentaro Wakui, Mikio Fujiwara, Kazuhiro   Ema, and Masahide Sasaki
quant-ph physics.optics