Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapour cell.

ABSTRACT: Entangled photon pairs, termed as biphotons, have been the benchmark tool for experimental quantum optics. The quantum-network protocols based on photon-atom interfaces have stimulated a great demand for single photons with bandwidth comparable to or narrower than the atomic natural linewidth. In the past decade, laser-cooled atoms have often been used for producing such biphotons, but the apparatus is too large and complicated for engineering. Here we report the generation of subnatural-linewidth (<6?MHz) biphotons from a Doppler-broadened (530?MHz) hot atomic vapour cell. We use on-resonance spontaneous four-wave mixing in a hot paraffin-coated ⁸⁷Rb vapour cell at 63?°C to produce biphotons with controllable bandwidth (1.9-3.2?MHz) and coherence time (47-94?ns). Our backward phase-matching scheme with spatially separated optical pumping is the key to suppress uncorrelated photons from resonance fluorescence. The result may lead towards miniature narrowband biphoton sources.

SUBMITTER: Shu C 

PROVIDER: S-EPMC5036144 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature