Quantum sensing with critical systems: impact of symmetry, imperfections, and decoherence

TL;DR

This paper explores quantum sensing using critical many-body states, analyzing how symmetries, imperfections, and decoherence affect their performance and identifying regimes where they outperform traditional states.

Contribution

It introduces a symmetry-based algorithm for optimal measurement strategies and compares the robustness of critical states with GHZ and spin-squeezed states under realistic conditions.

Findings

Critical states can outperform GHZ states in certain regimes.

Non-unitary deformations can enhance sensing precision.

Symmetry-preserving decoherence maintains criticality benefits.

Abstract

Entangled many-body states enable high-precision quantum sensing beyond the standard quantum limit. We develop interferometric sensing protocols based on quantum critical wavefunctions and compare their performance with Greenberger-Horne-Zeilinger (GHZ) and spin-squeezed states. Building on the idea of symmetries as a metrological resource, we introduce a symmetry-based algorithm to identify optimal measurement strategies. We illustrate this algorithm both for magnetic systems with internal symmetries and Rydberg-atom arrays with spatial symmetries. We study the robustness of criticality for quantum sensing under non-unitary deformations, symmetry-preserving and symmetry-breaking decoherence, and qubit loss -- identifying regimes where critical systems outperform GHZ states and showing that non-unitary deformation can even enhance sensing precision. Combined with recent results on log-depth preparation of critical wavefunctions, interferometric sensing in this setting appears increasingly promising.