Relative Phase Distribution and the Precision of Optical Phase Sensing in Quantum Metrology

TL;DR

This paper demonstrates that the relative phase distribution introduced by Luis and Sánchez-Soto accurately predicts the minimum phase sensing uncertainty in quantum metrology, matching the quantum Fisher information for pure states.

Contribution

It shows that the LSS relative phase distribution can be used to estimate the ultimate phase measurement precision in quantum metrology for pure states.

Findings

Fisher information from LSS distribution matches quantum Fisher information.

LSS distribution predicts minimum phase sensing uncertainty.

Results hold for several two-mode pure quantum states.

Abstract

One of the quantum metrology goals is to improve the precision in the measurement of a small optical phase introduced in one optical mode in an interferometer, i.e., phase sensing. In this paper, we obtain the relative phase distribution introduced by Luis and S\'anchez-Soto (LSS) [Phys. Rev. A $\mathbf{53}$, 495 (1996)] for several two-mode pure quantum light states useful in quantum metrology. We show that, within the numerical precision of our calculations, the Fisher information obtained from the LSS relative phase distribution is equal to the quantum Fisher information for the considered states (the average difference for the tested states is smaller than 0.1%). Our results indicate that the LSS relative phase distribution can be used to predict the minimum uncertainty possible in the process of phase sensing in quantum metrology, since this uncertainty depends on the quantum Fisher information, at least for pure states.