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arXiv · 2007.02586

Two-photon phase-sensing with single-photon detection

Panagiotis Vergyris·Charles Babin·Raphael Nold·Elie Gouzien·Harald Herrmann·Christine Silberhorn·Olivier Alibart·Sébastien Tanzilli·Florian Kaiser
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Abstract

Path-entangled multi-photon states allow optical phase-sensing beyond the shot-noise limit, provided that an efficient parity measurement can be implemented. Realising this experimentally is technologically demanding, as it requires coincident single-photon detection proportional to the number of photons involved, which represents a severe challenge for achieving a practical quantum advantage over classical methods. Here, we exploit advanced quantum state engineering based on superposing two photon-pair creation events to realise a new approach that bypasses this issue. In particular, optical phase shifts are probed with a two-photon quantum state whose information is subsequently effectively transferred to a single-photon state. Notably, without any multiphoton detection, we infer phase shifts by measuring the average intensity of the single-photon beam on a photodiode, in analogy to standard classical measurements. Importantly, our approach maintains the quantum advantage: twice as many interference fringes are observed for the same phase shift, corresponding to N=2 path-entangled photons. Our results demonstrate that the advantages of quantum-enhanced phase-sensing can be fully exploited in standard intensity measurements, paving the way towards resource-efficient and practical quantum optical metrology.

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Panagiotis Vergyris, Charles Babin, Raphael Nold, Elie Gouzien, Harald Herrmann, Christine Silberhorn, Olivier Alibart, Sébastien Tanzilli, Florian Kaiser. 2020-07-06. Two-photon phase-sensing with single-photon detection. https://doi.org/10.1063/5.0009527

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