Controllable Optical Frequency Converter and Its Applications
Kao-Fang Chang1, Yi-Hsin Chen1*, Chun-Yi Chen1, Ta-Pang Wang1, Yu-Sheng Wang1, Yong-Fan Chen2, Ying-Cheng Chen3, Ite A. Yu1
1Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
2Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
3Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
* Presenter:Yi-Hsin Chen,
We present a high-efficiency optical frequency converter based on a four-wave-mixing (FWM) transition in a cold ⁸⁷Rb ensemble. In this scheme, a probe and a coupling fields form a Λ-type electromagnetically induced transparency (EIT), and an additional driving field generates a sum-frequency with a wavelength difference of 15 nm relative to the probe field. We optimized the conversion efficiency (from the incident probe field to the generated signal field) up to 81% for applying both a classical light field and coherent single photons. Such photonic quantum bits are useful for connecting quantum systems operating at different frequencies in a quantum network. Moreover, the conversion efficiency is controllable by the detunings of the light fields due to the interference between two transition channels. The frequency converter served as quantum multiplexer and de-multiplexer can convert a single photon to carry a superposition state of two different colors qubits. The quantum device would be useful for quantum information processing.

Keywords: four-wave-mixing , electromagnetically induced transparency, qubit, quantum multiplexer