High‐Performance Telecom‐Wavelength Biphoton Source from a Hot Atomic Vapor Cell

Abstract

Telecom‐band quantum light sources are critical to the development of long‐distance quantum communication technologies. A high‐performance telecom‐wavelength biphoton source from a hot ⁸⁷Rb atomic vapor cell is reported. Time‐correlated biphotons are generated from the cascade‐type 5S_1/2–5P_3/2–4D_5/2 transition of ⁸⁷Rb via a spontaneous four‐wave mixing process. The maximum value of biphoton cross‐correlation to be 44(3) is achieved, under the condition of a high optical depth of 112(3), including two‐photon absorption, with a spectral width of approximately 300 MHz. The coincidence count rate of biphoton is estimated to be of the order of 38 000 cps mW⁻¹. It is believed that the telecom‐wavelength biphoton source from an atomic vapor cell can be applied in long‐distance quantum networks and practical quantum repeaters based on atom–photon interactions.