Correlated Noise Estimation with Quantum Sensor Networks

TL;DR

This paper develops a theoretical framework for estimating correlated noise in quantum sensor networks, revealing how quantum and classical correlations can enhance measurement sensitivity and identifying optimal states and protocols for such tasks.

Contribution

It introduces a new framework for correlated noise estimation in quantum sensors, highlighting the role of entanglement and classical correlations in achieving optimal sensitivity.

Findings

Optimal entangled probe states identified

A sensing protocol achieving fundamental measurement limits

Synergistic role of quantum and classical correlations

Abstract

We address the metrological problem of estimating collective stochastic properties imprinted on a network of quantum sensors. Canonical examples include center-of-mass quadrature fluctuations in a system of bosonic modes and correlated dephasing in an ensemble of qubits (e.g., spins), bosons, or fermions. We develop a theoretical framework to determine the limits of correlated (weak) noise estimation with quantum sensor networks and reveal the requirements for entanglement advantage. Notably, an advantage emerges from the synergistic interplay between quantum correlations of the sensors and ``classical'' correlations of the noises. We determine optimal entangled probe states and identify a sensing protocol -- reminiscent of a many-body echo -- that achieves the fundamental limits of measurement sensitivity for a broad class of problems, unveiling a route towards entanglement-enhanced metrology of correlated many-body phenomena.