Photonic quantum memory in two-level ensembles based on modulating the refractive index in time: equivalence to gradient echo memory

TL;DR

This paper introduces a quantum memory protocol using time-dependent refractive index modulation in two-level atomic ensembles, demonstrating its equivalence to gradient echo memory and discussing experimental feasibility.

Contribution

It proposes a novel quantum memory method based on refractive index modulation, expanding the toolkit for light storage in atomic ensembles.

Findings

Refractive index modulation can store light in two-level atomic ensembles.

The protocol is theoretically equivalent to gradient echo memory.

Potential for experimental implementation is discussed.

Abstract

We present a quantum memory protocol that allows to store light in ensembles of two-level atoms, e.g. rare-earth ions doped into a crystal, by modulating the refractive index of the host medium of the atoms linearly in time. We show that under certain conditions the resulting dynamics is equivalent to that underlying the gradient echo memory protocol, which relies on a spatial gradient of the atomic resonance frequencies. We discuss the prospects for an experimental implementation.