Interference and indistinguishability of photons

Peter Michler, Simone Luca Portalupi

Julian Münzberg, Christoph Dittel, Maxime Lebugle +4 more

John Gordon King, Malcolm Correll

Carlos F. D. Faurby, Lorenzo Carosini, Huan Cao +9 more

Indistinguishability between photons is a key requirement for scalable photonic quantum technologies. We experimentally demonstrate that partly distinguishable single photons can be purified to reach near-unity indistinguishability by the process of quantum interference with ancillary photons followed by heralded detection of a subset of them. We report on the indistinguishability of the purified photons by interfering two purified photons and show improvements in the photon indistinguishability of 2.774(3)% in the low-noise regime, and as high as 10.2(5)% in the high-noise regime.

Riccardo Albiero, Mathias Pont, Sarah E. Thomas +14 more

The generation of quantum states of many indistinguishable photons is a crucial resource for the realization of photonic computer architectures that can enable a quantum speedup and create fault-tolerant multi-party quantum networks. On the experimental side, the measurement of indistinguishability for a multi-photon state is a challenging task. In the case of a two-photon state, the photon indistinguishability is fully assessed by the visibility of the interference fringe of the Hong-Ou-Mandel (HOM) interference experiment on a balanced beam splitter. However, pairwise HOM experiments are unable to completely determine the multi-photon indistinguishability when more than two photons are involved [1]–[2].

Pieter Kok