Our Recent Advances in Optical Quantum Memory

Ying-Cheng Chen^1*

¹Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Ying-Cheng Chen, email:chenyc@pub.iams.sinica.edu.tw

Optical quantum memory is a device that can store a photonic quantum state in stationary atoms and then retrieve on demand. The ability of quantum memories to synchronize probabilistic events makes them a key component in long-distance quantum cryptography based on quantum repeater protocol and linear-optics-based quantum computation. This critical feature has motivated many groups to dedicate their research on developing high-performance quantum memories which characterized by a high fidelity, high efficiency, high capacity and long storage time. In this talk, I will first introduce our recent work to achieve coherent optical memories with a record-high storage efficiency of 92 % based on electromagnetically induced transparency in optically dense cold atomic ensembles. The requirements and difficulties to reach a high efficiency will be discussed. To realize the optical quantum memory, we then present our development of an ultra-bright, single-mode, and narrow-band photon-pair source that can locked to an atomic transition based on cavity-enhanced spontaneous parametric down conversion. Finally, I will present our preliminary results on quantum storage of heralded single photons in cold atomic ensembles and discuss future improvements towards a high efficiency and a high bandwidth.

Keywords: quantum memory, electromagnetically induced transparency, slow light, quantum repeater, single-photon source