Quantum noise and self-sustained radiation of PT-symmetric systems

TL;DR

This paper demonstrates that quantum noise breaking microreversibility causes PT-symmetric systems to become self-sustained radiation sources, highlighting a fundamental difference from Hermitian systems with potential implications for optical and quantum technologies.

Contribution

It reveals that quantum noise induces self-sustained radiation in PT-symmetric systems, a novel effect not present in Hermitian quantum systems.

Findings

Quantum noise breaks microreversibility in PT-symmetric systems.

PT-symmetric systems act as self-sustained radiation sources.

Distinction from Hermitian systems due to quantum noise effects.

Abstract

The observation that PT-symmetric Hamiltonians can have real-valued energy levels even if they are non-Hermitian has triggered intense activities, with experiments, in particular, focusing on optical systems, where Hermiticity can be broken by absorption and amplification. For classical waves, absorption and amplification are related by time-reversal symmetry. This work shows that microreversibility-breaking quantum noise turns PT-symmetric systems into self-sustained sources of radiation, which distinguishes them from ordinary, Hermitian quantum systems.