Enhanced dissipative criticality at an exceptional point

TL;DR

This paper shows that exceptional points in open quantum systems can amplify critical fluctuations and modify critical exponents, offering new ways to engineer critical behavior for quantum sensing.

Contribution

It demonstrates that combining exceptional points with dissipative phase transitions enhances critical scaling and provides a theoretical framework for this phenomenon.

Findings

Enhanced critical scaling observed at the exceptional point

Modified critical exponents due to Jordan-block dynamics

Potential applications in critical quantum sensing

Abstract

Exceptional points (EPs) represent non-Hermitian degeneracies where eigenvalues and eigenvectors coalesce, giving rise to enhanced sensitivity and critically damped dynamics. We demonstrate that when an EP coincides with a dissipative phase transition in an extended open Dicke model of two cavities coupled to a collective spin, the critical fluctuations are strongly amplified and governed by modified critical exponents. Numerical results reveal enhanced critical scaling in both the normal and superradiant phases, in agreement with an analytical theory based on EP-induced Jordan-block dynamics. Our results establish EPs as a mechanism to engineer critical scaling in open quantum systems, with potential applications to critical quantum sensing.