Entanglement-assisted quantum metrology

TL;DR

This paper explores how entanglement-assisted strategies can enhance quantum metrology, especially under noisy conditions, by using shared entanglement to improve measurement precision across various noise models.

Contribution

It introduces a framework applying shared entanglement to quantum metrology, demonstrating its usefulness in noisy environments and proposing an experimental test.

Findings

Entanglement assistance improves measurement precision in noisy quantum systems.

Shared entanglement is beneficial even when ancillas do not help in noiseless scenarios.

The approach is effective across multiple noise models and levels.

Abstract

Entanglement-assisted quantum communication employs pre-shared entanglement between sender and receiver as a resource. We apply the same framework to quantum metrology, introducing shared entanglement between the preparation and the measurement stage, namely using some entangled ancillary system that does not interact with the system to be sampled. This is known to be useless in the noiseless case, but was recently shown to be useful in the presence of noise. Here we detail how and when it can be of use. For example, surprisingly it is useful when randomly time sharing two channels where ancillas do not help (depolarizing). We show that it is useful for all levels of noise for many noise models and propose a simple experiment to test these results.