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.

中文翻译：

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磁调谐、稳健且高效的过滤系统，用于热原子蒸气中的空间多模量子存储器


温原子蒸气量子存储器简单而坚固，但会受到许多产生过量噪声的寄生过程的影响。对于在单光子状态下工作，输出光的精确过滤至关重要。在这里，我们报告了磁调谐吸收和法拉第滤波器的组合，两者都对光方向不敏感，可以停止驱动激光器并衰减杂散荧光和四波混合，同时传输写入和读出中生成的窄带斯托克斯和反斯托克斯光子流程。我们根据可调节的工作参数来描述这两种滤波器的特征。我们证明，在拉曼散射光子之间的相关性测量中应用定性观察到的滤波器后，信噪比显着增加。