Experimental demonstration of optimal unambiguous two-out-of-four quantum state elimination

Jonathan Webb, Ittoop Vergheese Puthoor, Joseph Ho, Jonathan Crickmore, Emma Blakely, Alessandro Fedrizzi, Anna Erika Elisabeth Andersson

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A core principle of quantum theory is that non-orthogonal quantum states cannot be perfectly distinguished with single-shot measurements. However, it is possible to exclude a subset of non-orthogonal states without error in certain circumstances. Here we implement a quantum state elimination measurement which unambiguously rules out two of four pure, non-orthogonal quantum states---ideally without error and with unit success probability. This is a generalized quantum measurement with six outcomes, where each outcome corresponds to excluding a pair of states. Our experimental realization uses single photons, with information encoded in a four-dimensional state using optical path and polarization degrees of freedom. The prepared state is incorrectly ruled out up to 3.3(2)% of the time.
Original languageEnglish
Article number023094
JournalPhysical Review Research
Issue number2
Publication statusPublished - 12 May 2023


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