Towards a High-Efficiency Optical Frequency Converter at Single-Photon Level
Kao-Fang Chang1, Yi-Hsin Chen1*, Yu-Sheng Wang1, Jun-Yi Chen1, Shuen-Chang Hung1, Ya-Fen Hsiao2, Ying-Cheng Chen2, Yong-Fan Chen3, Ite A. Yu1
1Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
2Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
3Department of Physics, National Cheng Kung University, Tainan, Taiwan
* presenting author:Yi-Hsin Chen,
Photons with a tunable frequency can carry information among various types of quantum devices. The quantum state transfer has potential applications in quantum information processing, such as quantum multiplexer/demultiplexer. Our optical frequency converter is based on the nonlinear electromagnetically-induced-transparency (EIT) effect as well as four-wave-mixing (FWM) effect in a cold 87Rb medium. We report a conversion efficiency of higher than 70% for continuous-wave laser fields, which enable a high repetition rate of the device. As the next step, we are about to convert the optical frequency towards single-photon level. We will compare the non-resonant FWM with resonant FWM frequency converters, and finally we discuss the methods for the improvement of conversion efficiency.

Keywords: EIT, four-wave mixing, frequency conversion