Physical Review Research (Sep 2021)

Probing the indistinguishability of single photons generated by Rydberg atomic ensembles

  • Auxiliadora Padrón-Brito,
  • Jan Lowinski,
  • Pau Farrera,
  • Klara Theophilo,
  • Hugues de Riedmatten

DOI
https://doi.org/10.1103/PhysRevResearch.3.033287
Journal volume & issue
Vol. 3, no. 3
p. 033287

Abstract

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We investigate the indistinguishability of single photons retrieved from collective Rydberg excitations in cold atomic ensembles. The Rydberg spin waves are created either by off-resonant two-photon excitation to the Rydberg state or by Rydberg electromagnetically induced transparency. To assess the indistinguishability of the generated single photons, we perform Hong-Ou-Mandel experiments between the single photons and weak coherent states of light. We analyze the indistinguishability as a function of the detection window, and we infer a high value of indistinguishability going from 89% for the full waveform to 98% for small detection windows, for the case of photons generated by off-resonant excitation. In the same way, we also investigate the indistinguishability of single photons generated by Rydberg EIT, showing values lower than those corresponding to single photons generated by off-resonant excitation. These results are relevant for the use of Rydberg atoms as quantum network nodes.