Initialisation protocol for efficient quantum memories using resolved hyperfine structure

TL;DR

This paper introduces a spectral preparation protocol for quantum memories in hyperfine-resolved materials, demonstrating improved efficiency and bandwidth in 167 Er3+:Y2SiO5 with potential for further enhancements.

Contribution

The paper presents a novel spectral preparation method that enhances quantum memory efficiency and bandwidth in hyperfine-resolved materials like 167 Er3+:Y2SiO5.

Findings

Achieved 22% quantum storage efficiency for 200 ns pulses.

Prepared spectrally isolated features with 18 dB absorption on a 1 dB background.

Identified experimental improvements for higher efficiency and bandwidth.

Abstract

We describe a quantum memory spectral preparation strategy that maximises memory efficiency and bandwidth in materials such as 167 Er3+:Y2SiO5 in a high field regime, where the hyperfine structure is resolved. We demonstrate the method in 167 Er3+:Y2SiO5 by preparing spectrally isolated 18 dB-absorbing features on a < 1 dB background. Using these features we create an atomic frequency comb and show quantum storage of 200 ns pulses with 22% efficiency, limited by the background absorption which arises from laser instability. We describe the experimental improvements needed to reach the material limits: O(1) s spin state storage, O(100) MHz bandwidth, and > 90% efficiency.