Critical metrology of minimally accessible anisotropic spin chains

TL;DR

This paper investigates quantum metrology in critical anisotropic spin chains with Dzyaloshinskii-Moriya interaction, analyzing how local measurements can effectively characterize global system properties and optimize parameter estimation.

Contribution

It introduces a detailed analysis of Fisher information for local and quasi-local measurements in anisotropic spin chains, revealing optimal regimes for system characterization.

Findings

Local measurements can effectively estimate global properties.

Correlations influence the precision of parameter estimation.

Optimal regimes depend on system parameters and measurement choices.

Abstract

We address quantum metrology in critical spin chains with anisotropy and Dzyaloshinskii-Moriya (DM) interaction, and show how local and quasi-local measurements may be exploited to characterize global properties of the systems. In particular, we evaluate the classical (magnetization) and quantum Fisher information of the relevant parameters for the density matrix of a single spin and that of a pair of spins ranging from nearest to sixth-nearest neighbors, to the limiting case of very distant spins. Our results allow us to elucidate the role of the different parameters and to individuate the optimal working regimes for the precise characterization of the system, also clarifying the effects of correlations on the estimation precision.