Witnesses of coherence and dimension from multiphoton indistinguishability tests

• URL: http://arxiv.org/abs/2104.09235v1
• Date: Mon, 19 Apr 2021 12:13:51 GMT
• Title: Witnesses of coherence and dimension from multiphoton indistinguishability tests
• Authors: Taira Giordani, Chiara Esposito, Francesco Hoch, Gonzalo Carvacho, Daniel J. Brod, Ernesto F. Galv\~ao, Nicol\`o Spagnolo, and Fabio Sciarrino
• Abstract summary: We experimentally measure a novel type of coherence witness that uses pairwise state comparisons to identify superpositions in a basis-independent way. Besides coherence witnesses, we show the measurements also serve as a Hilbert-space dimension witness.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Quantum coherence marks a deviation from classical physics, and has been studied as a resource for metrology and quantum computation. Finding reliable and effective methods for assessing its presence is then highly desirable. Coherence witnesses rely on measuring observables whose outcomes can guarantee that a state is not diagonal in a known reference basis. Here we experimentally measure a novel type of coherence witness that uses pairwise state comparisons to identify superpositions in a basis-independent way. Our experiment uses a single interferometric set-up to simultaneously measure the three pairwise overlaps among three single-photon states via Hong-Ou-Mandel tests. Besides coherence witnesses, we show the measurements also serve as a Hilbert-space dimension witness. Our results attest to the effectiveness of pooling many two-state comparison tests to ascertain various relational properties of a set of quantum states.

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