Narrow linewidth photon pair generation from polarized warm atomic gas using hollow optical pumping

Summary form only given. Entangled photon pair is key factor for realization of quantum communication, quantum information, etc. For long distance quantum communication, it is necessary to generate narrow band biphoton for interaction with atomic based quantum memory. In recent years, generation of time-frequency entangled photon pairs based on spontaneous four-wave mixing (SFWM) process in atomic ensemble have been reported [1-3]. Very recently, S. Chu et al. achieved generation of strongly correlated subnatural-linewidth biphoton from Doppler-broaden hot atomic ensemble [4]. The group used paraffin-coated
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Rb vapour cell and separated optical pumping effect for reduce noise of fluorescence from resonant coupling field. In this paper, we performed experiment for subnatural-linewidth biphoton generation from hot atomic ensembles by using a hollow optical pumping field and regular vapour cell, which are not special coated cell.