Demonstration of Sub-MHz-Linewidth Biphotons by Controlled Quantum Interference

Ravikumar Chinnarasu^1*, Chi-Yang Liu¹, Yi-Feng Ding¹, Ite A Yu¹, Chih-Sung Chuu¹

¹Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Ravikumar Chinnarasu, email:ravi.unom@gmail.com

Biphotons of narrow bandwidth and long temporal length have potential applications in realizing efficient light-matter interface and quantum communication. However, generation of these photons usually requires atomic ensembles with high optical depth or spontaneous parametric down-conversion with delicate optical cavities. We propose and demonstrate narrowband biphotons with sub-MHz bandwidth using detuned four-wave mixing in low-optical-depth atomic ensemble. The bandwidth of the biphotons is only limited by the ground-state decoherence rate. We also demonstrate the potential of shaping these photons.

Keywords: Entangle photons, Quantum Optics