DLCZ Filtering

We implement the DLCZ protocol to retrieve single photons from an atomic ensemble of Rb87 atoms and study second order quantum correlations, g^2(t) between the read and write photons when background noise photons are filtered. The noise photons are from emission back to the initialized state. The filtering is done using a vapor cell filled with 85Rb and and 47 Torr of Ar buffer gas. The buffer gas serves to attenuate noise photons (approximately 18 dB), while providing only minimal attenuation (approximately 1 dB) of signal photons. Using the filter, we observe an improvement of the g^2(t) correlation between 15%-35% depending upon detuning of the write beam from resonance.

See: "Simple and efficient absorption filter for single photons from a cold atom quantum memory" D. T. Stack, P.J. Lee, Q. Quraishi, Optics Express, 23 (5), 6822-6832, arxiv 1411.7430 (2015)