Non-Equilibrium Criticality-Enhanced Quantum Sensing with Superconducting Qubits

TL;DR

This paper demonstrates a superconducting qubit-based quantum sensor leveraging non-equilibrium dynamics and criticality to achieve high-precision parameter estimation across a broad range of conditions.

Contribution

It unifies quantum criticality and non-equilibrium dynamics in a superconducting platform for enhanced quantum sensing without complex measurements.

Findings

Achieved near-Heisenberg-limited precision using simple measurements.

Performance surpasses localized regime across extended phase.

Utilized a 9-qubit superconducting device for experimental validation.

Abstract

Exploiting quantum features allows for estimating external parameters with precisions well beyond the capacity of classical sensors, a phenomenon known as quantum-enhanced precision. Quantum criticality has been identified as a resource for achieving such enhancements with respect to the probe size. However, they demand complex probe preparation and measurement and the achievable enhancement is ultimately restricted to narrow parameter regimes. On the other hand, non-equilibrium probes harness dynamics, enabling quantum-enhanced precision with respect to time over a wide range of parameters through simple probe initialization. Here, we unify these approaches through a Stark-Wannier localization platform, where competition between a linear gradient field and particle tunneling enables quantum-enhanced sensitivity across an extended parameter regime. The probe is implemented on a 9-qubit superconducting quantum device, in both single- and double-excitation subspaces, where we explore its performance in the extended phase, the critical point and the localized phase. Despite employing only computational-basis measurements we have been able to achieve near-Heisenberg-limited precision by combining outcomes at distinct evolution times. In addition, we demonstrate that the performance of the probe in the entire extended phase is significantly outperforming the performance in the localized regime. Our results highlight Stark-Wannier systems as versatile platforms for quantum sensing, where the combination of criticality and non-equilibrium dynamics enhances precision over a wide range of parameters without stringent measurement requirements.