Enhancement of sensitivity near exceptional points in dissipative qubit-resonator systems

TL;DR

This paper proposes a non-Hermitian quantum sensor leveraging dissipation near exceptional points to significantly enhance sensitivity in detecting coupling variations in a qubit-resonator system, confirmed by theory and experiment.

Contribution

It introduces a protocol for using dissipation and exceptional points to improve quantum sensing, demonstrating both theoretical and experimental sensitivity enhancement.

Findings

Sensitivity diverges at the exceptional point

The protocol effectively removes noisy outcomes

Experimental results confirm theoretical predictions

Abstract

Dissipation usually plays a negative role in quantum metrological technologies, which aim to improve measurement precision by leveraging quantum effects that are vulnerable to environment-induced decoherence. Recently, it has been demonstrated that dissipation can actually be used as a favorable resource for enhancing the susceptibility of signal detection. However, demonstrations of such enhancement for detecting physical quantities in open quantum systems are still lacking. Here we propose and demonstrate a protocol for realizing such non-Hermitian quantum sensors for probing the coupling between a qubit and a resonator subjecting to energy dissipations. The excitation-number conversion associated with the no-jump evolution trajectory enables removal of the noisy outcomes with quantum jumps, implementing the exceptional point (EP), where the Rabi splitting exhibits a divergent behavior in response to a tiny variation of the effective coupling. The sensitivity enhancement near the EP is confirmed by both theoretical calculation and experimental measurement.