Experimental ancilla-assisted phase-estimation in a noisy channel

TL;DR

This paper demonstrates experimentally that using an ancilla in quantum phase estimation can significantly improve measurement accuracy in high-noise optical environments by selecting configurations less affected by noise.

Contribution

It introduces an ancilla-assisted method for phase estimation that enhances robustness against noise in quantum metrology experiments.

Findings

Ancilla improves phase estimation accuracy in noisy channels

Coherent coupling helps select noise-resistant configurations

Experimental validation in optical phase estimation

Abstract

The metrological ability of carefully designed probes can be spoilt by the presence of noisy processes occurring during their evolution. The noise is responsible for altering the evolution of the probes in such a way that bear little or no information on the parameter of interest, hence spoiling the signal-to-noise ratio of any possible measurement. Here we show an experiment in which the introduction of an ancilla improves the estimation of an optical phase in the high-noise regime. The advantage is realised by the coherent coupling of the probe and the ancilla at the initialisation and the measurement state, which generate and then select a subset of overall configurations less affected by the noise process.