Optical phase estimation via coherent state and displaced photon counting

TL;DR

This paper introduces a novel displaced-photon counting detection scheme for optical phase estimation that surpasses traditional homodyne and heterodyne methods, achieving near-quantum limit precision with practical implementation.

Contribution

The paper proposes and experimentally demonstrates a new displaced-photon counting method that improves phase sensing performance beyond standard measurements.

Findings

Displaced-photon counting outperforms homodyne and heterodyne detection in phase estimation.

The scheme achieves near-quantum limit precision in practical conditions.

Experimental results confirm the scheme's robustness against imperfections.

Abstract

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.