Slow polaritons with orbital angular momentum in atomic gases

TL;DR

This paper explores the use of polariton formalism to study slow light propagation with orbital angular momentum in cold atomic gases, demonstrating vortex transfer during storage and retrieval of light.

Contribution

It introduces a scheme for transferring optical vortices from control to probe fields in a tripod atomic configuration, enabling vortex storage and retrieval in atomic gases.

Findings

Efficient vortex transfer during probe storage and retrieval.

Conditions for lossless propagation of vortex-carrying probe beams.

Feasibility of experimental implementation with rubidium or sodium atoms.

Abstract

Polariton formalism is applied for studying the propagation of a probe field of light in a cloud of cold atoms influenced by two control laser beams of larger intensity. The laser beams couple resonantly three hyperfine atomic ground states to a common excited state thus forming a tripod configuration of the atomic energy levels involved. The first control beam can have an optical vortex with the intensity of the beam going to zero at the vortex core. The second control beam without a vortex ensures the loseless (adiabatic) propagation of the probe beam at a vortex core of the first control laser. We investigate the storage of the probe pulse into atomic coherences by switching off the control beams, as well as its subsequent retrieval by switching the control beams on. The optical vortex is transferred from the control to the probe fields during the storage or retrieval of the probe field. We analyze conditions for the vortex to be transferred efficiently to the regenerated probe beam and discuss possibilities of experimental implementation of the proposed scheme using atoms like rubidium or sodium.