Room Temperature Atomic Frequency Comb Memory for Light

TL;DR

This paper demonstrates room temperature atomic frequency comb quantum memory in alkali vapour, enabling coherent storage and retrieval of pulsed light with enhanced efficiency through interference effects.

Contribution

It introduces a novel room temperature atomic frequency comb protocol using velocity-selective optical pumping in caesium vapor for broadband quantum memory.

Findings

Achieved coherent storage and retrieval of 2 ns pulses.

Demonstrated multi-temporal mode storage with 8 ns and 12 ns recall times.

Enhanced recall efficiency via interference effects from dual transitions.

Abstract

We demonstrate coherent storage and retrieval of pulsed light using the atomic frequency comb quantum memory protocol in a room temperature alkali vapour. We utilise velocity-selective optical pumping to prepare multiple velocity classes in the $F=4$ hyperfine ground state of caesium. The frequency spacing of the classes is chosen to coincide with the $F'=4 - F'=5$ hyperfine splitting of the $6^2$P$_{3/2}$ excited state resulting in a broadband periodic absorbing structure consisting of two usually Doppler-broadened optical transitions. Weak coherent states of duration $2\,\mathrm{ns}$ are mapped into this atomic frequency comb with pre-programmed recall times of $8\,\mathrm{ns}$ and $12\,\mathrm{ns}$, with multi-temporal mode storage and recall demonstrated. Utilising two transitions in the comb leads to an additional interference effect upon rephasing that enhances the recall efficiency.