Generation of Biphoton with Long Correlation Time in Cold Atoms

Abstract

Driven by the desire of narrow‐band photon pairs source, in this MPhil thesis work, we demonstrate the generation of photon pairs with controllable coherence time up to 1.72 microseconds, using spontaneous four‐wave mixing with electromagnetically induced transparency in a laser‐cooled atomic ensemble with an optical depth (OD) as high as 130. At such a high OD, we find that the pump laser intensity profile has a significant effect on the time‐frequency entangled two‐photon waveform. We also confirm  the  quantum  particle  nature  of  heralded  narrow‐band  single  photons generated from this source.