Quantum memory is a fundamental building block for large-scale quantum networks. On-demand optical storage with a large bandwidth, a high multimode capacity and an integrated structure simultaneously is crucial for practical application. However, this has not been demonstrated yet. Here, we fabricate an on-chip waveguide in a 151Eu3+:Y2SiO5 crystal with insertion losses of 0.2 dB, and propose a novel pumping scheme to enable spin-wave atomic frequency comb (AFC) storage with a bandwidth of 11 MHz inside the waveguide. Based on this, we demonstrate the storage of 200 temporal modes using the AFC scheme and conditional on-demand storage of 100 temporal modes using the spin-wave AFC scheme. The interference visibility between the readout light field and the reference light field is 99.0%±0.6% and 97%±3% for AFC and spin-wave AFC storage, respectively, indicating the coherent nature of this low-loss, multimode and integrated storage device.
@article{arxiv.2205.12762,
title = {On-demand multimode optical storage in a laser-written on-chip waveguide},
author = {Ming-Xu Su and Tian-Xiang Zhu and Chao Liu and Zong-Quan Zhou and Chuan-Feng Li and Guang-Can Guo},
journal= {arXiv preprint arXiv:2205.12762},
year = {2022}
}