Storing and controlling heralded single photon sent by the cavity-enhanced SPDC on an EIT-based quantum memory

Pin Ju Tsai^1,3*, Ya Fen Hsiao^1,2, Ying Cheng Chen¹

¹Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
²Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica and National Central University, Taipei, Taiwan
³Department of Physics, National Taiwan University, Taipei, Taiwan

* Presenter:Pin Ju Tsai, email:cditim@hotmail.com

Quantum storage and manipulation the single photon waveform is an important technology in optical quantum information processing. A scheme of quantum memory (QM) called electromagnetically induced transparency (EIT) in the atomic system provides a platform, that makes the properties of the photon can be controlled directly. The most common photon source for atomic QM is based on the spontaneous four-wave-mixing (sFWM) process on the same atomic species system. Since the operating frequency of photons that be generated exactly match the atomic QM, that can be used on the atomic QM directly. However, the complicated setup of system set the limitation in the real application. To overcome this issue, the cavity-enhanced spontaneous parametric down conversion (SPDC) source provided a solution with a compact configuration. This is helpful for achieving scalable optical quantum information processing. In this work, we realized the quantum storage of heralded single photon on an EIT-based QM in cold atomic ensembles. A cavity-enhanced SPDC source generated the narrow-band (6.6MHz), frequency-nondegenerate photon pair. The idler photons (780nm) are used to indicate the signal photon (locked to cesium D₂-line, 852nm) be sent out from the source. By the storage protocol that initiates by the idler photons, the signal photons are stored in an EIT-QM with a storage efficiency of 32%. Furthermore, by using a series of power of the reading fields, we also demonstrated the manipulation of single photon waveform further to enhance the nonclassical nature of the photon pair. Our work achieved the connection between the atomic system and solid-state photon source, which is an important step towards the scalable quantum repeater for long-distance quantum networks.

Keywords: Quantum memory, Electromagnetically-induced-transparency, Single photon source, Cavity-enhanced spontaneous parametric down-conversion