Anomalous Behaviors of Quantum Emitters in Non-Hermitian Baths

TL;DR

This paper explores the unconventional behaviors of quantum emitters coupled to non-Hermitian baths, revealing phenomena like bound states, spatial amplification, and power-law decay that differ from Hermitian systems.

Contribution

It demonstrates novel quantum emitter dynamics in non-Hermitian environments, including bound states and decay behaviors not seen in Hermitian systems.

Findings

Bound states inside the complex dispersion loop due to non-Hermitian skin effect

Photon emission showing spatial amplification distinct from free propagation

Emitter decay following a power law in non-Hermitian baths

Abstract

Both non-Hermitian systems and the behaviour of emitters coupled to structured baths have been studied intensely in recent years. Here we study the interplay of these paradigmatic settings. In a series of examples, we show that a single quantum emitter coupled to a non-Hermitian bath displays a number of unconventional behaviours, many without Hermitian counterpart. We first consider a unidirectional hopping lattice whose complex dispersion forms a loop. We identify peculiar bound states inside the loop as a manifestation of the non-Hermitian skin effect. In the same setting, emitted photons may display spatial amplification markedly distinct from free propagation, which can be understood with the help of the generalized Brillouin zone. We then consider a nearest-neighbor lattice with alternating loss. We find that the long-time emitter decay always follows a power law, which is usually invisible for Hermitian baths. Our work points toward a rich landscape of anomalous quantum emitter dynamics induced by non-Hermitian baths.