Squeezing as a resource to counteract phase diffusion in optical phase estimation

TL;DR

This paper investigates how squeezing can improve optical phase estimation under non-Gaussian phase noise, especially when applied after phase diffusion, and evaluates the effectiveness of homodyne detection in these scenarios.

Contribution

It introduces a novel analysis of squeezing used after phase noise to enhance estimation sensitivity and assesses the optimality of homodyne detection in realistic noisy conditions.

Findings

Squeezing after phase diffusion significantly increases quantum Fisher information.

Homodyne detection remains effective but is scenario-dependent.

Post-noise squeezing improves phase estimation sensitivity.

Abstract

We address a phase estimation scheme using Gaussian states in the presence of non-Gaussian phase noise. At variance with previous analysis, we analyze situations in which the noise occurs before encoding phase information. In particular, we study how squeezing may be profitably used before or after phase diffusion. Our results show that squeezing the probe after the noise greatly enhances the sensitivity of the estimation scheme, as witnessed by the increase of the quantum Fisher information. We then consider a realistic setup where homodyne detection is employed at the measurement stage, and address its optimality as well as its performance in the two different scenarios.