Optical non-reciprocity of cold atom Bragg mirrors in motion

TL;DR

This paper demonstrates how moving cold atom multilayers can break optical reciprocity, enabling high-contrast non-reciprocal light transmission with potential applications in optical isolation.

Contribution

It introduces a novel scheme using moving cold atom Bragg mirrors to achieve significant optical non-reciprocity in linear, passive media.

Findings

Achieved around 95% forward-backward transmission contrast at atomic speeds.

Demonstrated all-optical enhancement of non-reciprocity in multilevel atomic systems.

Opened new possibilities for optical isolation using cold atom multilayers.

Abstract

Reciprocity is fundamental to light transport and is a concept that holds also in rather complex systems. Yet, reciprocity can be switched off even in linear, isotropic and passive media by setting the material structure into motion. In highly dispersive multilayers this leads to a fairly large forward-backward asymmetry in the pulse transmission. Moreover, in multilevel systems, this transport phenomenon can be all-optically enhanced. For atomic multilayer structures made of three-level cold Rubidium 87 atoms, for instance, forward-backward transmission contrast around 95 per cent can be obtained already at atomic speeds in the meter per second range. The scheme we illustrate may open up avenues for optical isolation that were not previously accessible.