Bright, low-noise source of single photons at 780 nm with improved phase-matching in rubidium vapor

Future optical quantum networks could benefit from single photons that couple well to atoms, for realizing, e.g., quantum memories and deterministic photonic gates. However, the efficient generation of such photons remains a difficult challenge. Recently, we demonstrated a bright multiplexed source of indistinguishable single photons with tunable GHz-bandwidth based on four-wave-mixing in rubidium vapor [Davidson et al. 2021 New J. Phys. 23 073050]. Here we report on an improved implementation of this photon source. The new implementation employs a frequency-detuning regime that is better phase matched, a spatial-alignment procedure using single-mode fibers, a different rubidium isotope, and higher vapor-cell transmission. Characterization of the source is performed using superconducting-nanowire detectors with higher detection efficiency and lower jitter. Our source produces single photons with detected heralding efficiency of over 20%, Hong-Ou-Mandel interference visibility of 88%, generation rate of over 100 kilo-counts per second, and signal-to-noise ratio greater than 100, making it suitable for quantum information processing with photons.