A Single-Photon-compatible Telecom-C-Band Quantum Memory in a Hot Atomic Gas

The efficient storage and on-demand retrieval of quantum optical states that are compatible with the telecommunications C-band is a requirement for future terrestrial-based quantum optical networking. Spectrum in the C-band minimises optical fiber-propagation losses, and broad optical bandwidth facilitates high-speed networking protocols. Here we report on a telecommunication wavelength and bandwidth compatible quantum memory. Using the Off-Resonant Cascaded Absorption protocol in hot 87 Rb vapour, we demonstrate a total memory efficiency of 20 . 90(1) % with a Doppler-limited storage time of 1 . 10(2) ns. We characterise the memory performance with weak coherent states, demonstrating signal-to-noise ratios greater than unity for mean photon number inputs above 4 . 5(6) × 10 − 6 per pulse.