Persistent quantum advantage with definite photon-number states in lossy multiple-phase estimation

TL;DR

This paper introduces a robust quantum multiple-phase estimation scheme using definite photon-number states that maintains quantum advantage despite photon loss, advancing practical quantum sensing technologies.

Contribution

The authors develop an optimal estimation scheme employing multi-mode definite photon-number states that are resilient to photon loss, outperforming classical and NOON state methods.

Findings

DPN states sustain quantum enhancement under all photon loss levels

The scheme outperforms classical benchmarks with coherent states

Generalizes earlier NOON state approaches

Abstract

Multiple-phase estimation exploiting quantum states has broad applications in novel sensing and imaging technologies. However, the unavoidable presence of lossy environments in practical settings often diminishes the precision of phase estimations. To address this challenge, we propose an optimal multiple-phase estimation scheme that is inherently robust against photon loss, ensuring a persistent quantum advantage across all levels of photon loss. The scheme employs a multi-mode definite photon-number (DPN) state with weights optimized for given levels of photon loss. We theoretically demonstrate that the DPN state can sustain quantum enhancement in estimation precision under all levels of photon loss, compared to the classical benchmark that employs a coherent state input. The proposed scheme using DPN states generalizes earlier studies employing NOON states, which are only optimal when photon loss is small. We believe that our study, demonstrating persistent robustness to photon loss, paves the way for significant advancements in quantum-enhanced sensing technologies, enabling practical applications and quantum advantages in real-world scenarios.