Optical Memory in a Microfabricated Rubidium Vapor Cell

Scalability presents a central platform challenge for the components of current quantum network implementations that can be addressed by microfabrication techniques. We demonstrate a high-bandwidth optical memory using a warm alkali atom ensemble in a microfabricated vapor cell compatible with wafer-scale fabrication. By applying an external tesla-order magnetic field, we explore a novel ground-state quantum memory scheme in the hyperfine Paschen-Back regime, where individual optical transitions can be addressed in a Doppler-broadened medium. Working on the ${}^{87}$Rb D${}_2$ line, where deterministic quantum dot single-photon sources are available, we demonstrate bandwidth-matching with hundreds of megahertz broad light pulses keeping such sources in mind. For a storage time of 80 ns we measure an end-to-end efficiency of ${\eta }_{e2e}^{\text{80ns}}=3.12(17)\mathrm{\%}$, corresponding to an internal efficiency of ${\eta }_{\text{int}}^{\text{0ns}}=24(3)\mathrm{\%}$, while achieving a signal-to-noise ratio of $\text{SNR}=7.9(8)$ with coherent pulses at the single-photon level.