Photon echoes generated by reversing magnetic field gradients in a rubidium vapour

TL;DR

This paper introduces a photon echo quantum memory scheme using magnetic field gradient reversal in rubidium vapour, avoiding complex pulse sequences and demonstrating proof of principle experimentally.

Contribution

It presents a novel photon echo quantum memory method that employs magnetic field gradient inversion, simplifying control requirements compared to previous schemes.

Findings

Successful experimental demonstration in rubidium vapour

Rephasing achieved by magnetic field gradient inversion

Potential for simplified quantum memory implementation

Abstract

We propose a photon echo quantum memory scheme using detuned Raman coupling to long lived ground states. In contrast to previous 3-level schemes based on controlled reversible inhomogeneous broadening that use sequences of $\pi$-pulses, the scheme does not require accurate control of the coupling dynamics to the ground states. We present a proof of principle experimental realization of our proposal using rubidium atoms in a warm vapour cell. The Raman resonance line is broadened using a magnetic field that varies linearly along the direction of light propagation. Inverting the magnetic field gradient rephases the atomic dipoles and re-emits the light pulse in the forward direction.