A strong no-go theorem and experiment for the Wigner's friend paradox

Geoff J. Pryde

doi:10.1117/12.2592509

5 March 2021 A strong no-go theorem and experiment for the Wigner's friend paradox

Geoff J. Pryde

Proceedings Volume 11700, Optical and Quantum Sensing and Precision Metrology; 117000W (2021) https://doi.org/10.1117/12.2592509
Event: SPIE OPTO, 2021, Online Only

Abstract

How can we address the idea of observers in quantum mechanics? The long-standing Wigner’s friend thought experiment provides a conceptual framework for thinking about this question. It considers the the difficulty of reconciling unitary, evolution of systems and non-unitary state update after a making observations. Following from a recent suggested protocol with two friends that share and entangled state, we prove and investigate, in a photonic experiment, a strong no-go theorem for this Wigner’s friend scenario. Specifically, if quantum mechanics applies at the scale of observers, then there are constraints on the set of assumptions: locality; no-superdeterminism; and absoluteness of observed events. We note that this new theorem places strictly stronger constraints on physical reality than Bell’s theorem.

Conference Presentation

Citation Download Citation

Geoff J. Pryde "A strong no-go theorem and experiment for the Wigner's friend paradox", Proc. SPIE 11700, Optical and Quantum Sensing and Precision Metrology, 117000W (5 March 2021); https://doi.org/10.1117/12.2592509

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