A quantum memory, for storing and retrieving flying photonic quantum states, is a key interface for realizing long-distance quantum communication and large-scale quantum computation. While many experimental schemes of high storage-retrieval efficiency have been performed with weak coherent light pulses, all quantum memories for true single photons achieved so far have efficiencies far below 50%, a threshold value for practical applications. Here, we report the demonstration of a quantum memory for single-photon polarization qubits with an efficiency of >85% and a fidelity of >99 %, basing on balanced two-channel electromagnetically induced transparency in laser-cooled rubidium atoms. For the single-channel quantum memory, the optimized efficiency for storing and retrieving single-photon temporal waveforms can be as high as 90.6 %. Our result pushes the photonic quantum memory closer to its practical applications in quantum information processing.
@article{arxiv.2004.03123,
title = {Efficient quantum memory for single photon polarization qubits},
author = {Y. Wang and J. Li and S. Zhang and K. Su and Y. Zhou and K. Liao and S. Du and H. Yan and S. L. Zhu},
journal= {arXiv preprint arXiv:2004.03123},
year = {2020}
}