Asymptotically optimal joint phase and dephasing strength estimation using spin-squeezed states

TL;DR

This paper presents a protocol using spin-squeezed states for optimal simultaneous estimation of phase and dephasing strength, achieving precision close to fundamental quantum limits, with broad applicability to noise models in quantum metrology.

Contribution

It introduces an explicit N-qubit protocol with spin-squeezed states for joint parameter estimation that reaches asymptotic quantum bounds, extending to various noise models via quantum error correction.

Findings

Achieves asymptotically optimal precision in joint phase and dephasing estimation.

Utilizes one-axis-twisted spin-squeezed states for enhanced measurement.

Applicable to a wide class of noise models through error correction techniques.

Abstract

We show an explicit $N$-qubit protocol involving one-axis-twisted spin squeezed states, that allows for simultaneous phase and dephasing strength estimation with precision that asymptotically matches fundamental quantum metrological bounds. The relevance of the protocol goes beyond this particular model, since any uncorrelated noise quantum metrological model, that allows for at most constant asymptotic quantum enhancement, can be reduced to this problem via an appropriately tailored quantum error-correction procedure.