Nonreciprocal transition between two nondegenerate energy levels

TL;DR

This paper introduces a method to achieve nonreciprocal transitions between nondegenerate energy levels, enabling asymmetric light-matter interactions and potential nonreciprocal devices across various physical systems.

Contribution

It presents a generic approach to realize nonreciprocal transitions using a cyclic three-level atom system with synthetic magnetism and reservoir engineering.

Findings

Demonstrates nonreciprocal transition in a three-level atom system

Proposes a single-photon nonreciprocal transporter design

Shows potential for atom-mediated nonreciprocal devices

Abstract

Stimulated emission and absorption are two fundamental processes of light-matter interaction, and the coefficients of the two processes should be equal in general. However, we will describe a generic method to realize significant difference between the stimulated emission and absorption coefficients of two nondegenerate energy levels, which we refer to as nonreciprocal transition. As a simple implementation, a cyclic three-level atom system, comprising two nondegenerate energy levels and one auxiliary energy level, is employed to show nonreciprocal transition via a combination of synthetic magnetism and reservoir engineering. Moreover, a single-photon nonreciprocal transporter is proposed using two one dimensional semi-infinite coupled-resonator waveguides connected by an atom with nonreciprocal transition effect. Our work opens up a route to design atom-mediated nonreciprocal devices in a wide range of physical systems.