Distributed quantum phase estimation with entangled photons

TL;DR

This paper demonstrates distributed quantum phase estimation using entangled photons, achieving Heisenberg limit sensitivity and surpassing shot-noise limits through innovative entanglement and multiple passes.

Contribution

It introduces a novel distributed quantum sensing protocol with entangled photons and multiple passes, achieving significant error reduction below classical limits.

Findings

Error reduction up to 4.7 dB below shot-noise limit

Distributed sensing with entangled photons enhances sensitivity

Multiple passes of phase shifters improve measurement precision

Abstract

Distributed quantum metrology can enhance the sensitivity for sensing spatially distributed parameters beyond the classical limits. Here we demonstrate distributed quantum phase estimation with discrete variables to achieve Heisenberg limit phase measurements. Based on parallel entanglement in modes and particles, we demonstrate distributed quantum sensing for both individual phase shifts and an averaged phase shift, with an error reduction up to 1.4 dB and 2.7 dB below the shot-noise limit. Furthermore, we demonstrate a combined strategy with parallel mode entanglement and multiple passes of the phase shifter in each mode. In particular, our experiment uses six entangled photons with each photon passing the phase shifter up to six times, and achieves a total number of photon passes N=21 at an error reduction up to 4.7 dB below the shot-noise limit. Our research provides a faithful verification of the benefit of entanglement and coherence for distributed quantum sensing in general quantum networks.