Nonreciprocal PT-symmetric phase transition in a non-Hermitian chiral quantum optical system

TL;DR

This paper demonstrates a nonreciprocal parity-time-symmetric phase transition in a non-Hermitian chiral quantum system, revealing new quantum phenomena driven by directional dissipation, even with reciprocal atom-resonator coupling.

Contribution

It introduces the first observation of nonreciprocal PT-symmetric phase transition caused by directional dissipation in a non-Hermitian quantum system, independent of reciprocal coupling.

Findings

Nonreciprocal PT-symmetric phases occur despite reciprocal atom-resonator coupling.

Nonreciprocal photon blockade is observed in the nonreciprocal phase region.

The results deepen understanding of nonreciprocal and non-Hermitian quantum physics.

Abstract

Phase transitions, non-Hermiticity and nonreciprocity play central roles in fundamental physics. However, the triple interplay of these three fields is of lack in the quantum domain. Here, we show nonreciprocal parity-time-symmetric phase transition in a non-Hermitian chiral quantum electrodynamical system, caused by the directional system dissipation. In remarkable contrast to previously reported nonreciprocal phase transitions, the nonreciprocal parity-time-symmetric phases appear even when the atom-resonator coupling is reciprocal. Nonreciprocal photon blockade is obtained in the nonreciprocal phase region. These results may deepen the fundamental insight of nonreciprocal and non-Hermitian quantum physics, and also open a new door for unconventional quantum manipulation.