Warm atomic vapor quantum memories are simple and robust, yet suffer from a number of parasitic processes which produce excess noise. For operating in a single-photon regime precise filtering of the output light is essential. Here we report a combination of magnetically tuned absorption and Faraday filters, both light-direction-insensitive, which stop the driving lasers and attenuate spurious fluorescence and four-wave mixing while transmitting narrowband Stokes and anti-Stokes photons generated in write-in and readout processes. We characterize both filters with respect to adjustable working parameters. We demonstrate a significant increase in the signal to noise ratio upon applying the filters seen qualitatively in measurements of correlation between the Raman-scattered photons.
@article{arxiv.1507.08963,
title = {Magnetically tuned, robust and efficient filtering system for spatially multimode quantum memory in warm atomic vapors},
author = {Michał Dąbrowski and Radosław Chrapkiewicz and Wojciech Wasilewski},
journal= {arXiv preprint arXiv:1507.08963},
year = {2017}
}