# Time-reversed and coherently-enhanced memory: A single-mode quantum atom-optic memory without a cavity

## TL;DR

This paper introduces a cavity-free, coherently-enhanced quantum memory technique using interference to boost atom-light coupling, achieving high efficiency and long storage times in cold rubidium-87 atoms.

## Contribution

It demonstrates a novel interference-based enhancement method for quantum memory that eliminates the need for optical cavities, with experimental validation showing high efficiency and extended storage.

## Key findings

- Efficiency of 72% with a 5% margin
- Storage lifetime of 110 microseconds
- Effective cavity-free enhancement of atom-light coupling

## Abstract

The efficiency of an ensemble-based optical quantum memory depends critically on the strength of the atom-light coupling. An optical cavity is an effective method to enhance atom-light coupling strength, with the drawback that cavities can be difficult to integrate into a memory setup. In this work we show coherent enhancement of atom-light coupling via an interference effect. The light to be absorbed into the atomic ensemble is split and used to drive the atoms from opposite ends of the ensemble. We compare this method theoretically to a cavity enhanced scheme and present experimental results for our coherent enhancement in cold rubidium-87 atoms that show an efficiency of $72\pm5\%$ and a storage lifetime of $110\pm 10$ us.