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.
@article{arxiv.2103.04581,
title = {Initialisation protocol for efficient quantum memories using resolved hyperfine structure},
author = {James Stuart and Morgan Hedges and Rose Ahlefeldt and Matthew Sellars},
journal= {arXiv preprint arXiv:2103.04581},
year = {2021}
}