Using a single neutral 87Rb atom held in an optical trap, and "quantum jump" detection of single-photon-initiated state changes, we demonstrate a single-photon quantum jump photodetector (QJPD) with intrinsically narrow bandwidth and strong rejection of out-of-band photons, of interest for detecting weak optical signals in the presence of a strong broadband background. By analyzing fluorescence photon count distributions for the bright and dark states with and without excitation, we measure quantum efficiency of 2.9(2)×10−3, a record for single-pass quantum jump production, and signal-photon-unprovoked "dark jump" rate - analogous to the dark count rate of other detectors - 3(10)×10−3 jumps per second during passive accumulation plus 4.0(4)×10−3 jumps per readout, orders of magnitude below those of traditional single-photon detectors. Available methods can substantially improve QJPD quantum efficiency, dark jump rate, bandwidth and tunability.
@article{arxiv.2403.08674,
title = {Quantum jump photodetector for narrowband photon counting with a single atom},
author = {Laura Zarraoa and Romain Veyron and Tomas Lamich and Lorena C. Bianchet and Morgan W. Mitchell},
journal= {arXiv preprint arXiv:2403.08674},
year = {2024}
}