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Wigner’s Friend Depends on Self-Contradictory Quantum Amplification

Knight, Andrew (2022) Wigner’s Friend Depends on Self-Contradictory Quantum Amplification. [Preprint]

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Abstract

In a recent paper, Zukowski and Markiewicz showed that Wigner’s Friend (and, by extension, Schrodinger’s Cat) can be eliminated as physical possibilities on purely logical grounds. I validate this result and demonstrate the source of the contradiction in a simple experiment in which a scientist S attempts to measure the position of object |O⟩ = |A⟩S +|B⟩S by using measuring device M chosen so that |A⟩M ≈ |A⟩S and |B⟩M ≈ |B⟩S. I assume that the measurement occurs by
quantum amplification without collapse, in which M can entangle with O in a way that remains reversible by S for some nonzero time period. This assumption implies that during this “reversible” time period, |A⟩M ̸= |A⟩S and |B⟩M ̸= |B⟩S – i.e., the macroscopic pointer state to which M evolves is uncorrelated to the position of O relative to S. When the scientist finally observes the measuring device, its macroscopic pointer state is uncorrelated to the object in position |A⟩S or |B⟩S, rendering the notion of “reversible measurement” a logical contradiction.


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Item Type: Preprint
Creators:
CreatorsEmailORCID
Knight, Andrewaknight@alum.mit.edu0000-0003-0274-1681
Keywords: reversibility; Schrodinger's Cat; Wigner's Friend; von Neumann quantum amplification; logical contradiction
Subjects: Specific Sciences > Physics > Quantum Mechanics
Depositing User: Dr. Andrew Knight
Date Deposited: 19 Feb 2022 00:31
Last Modified: 19 Feb 2022 00:31
Item ID: 20223
Subjects: Specific Sciences > Physics > Quantum Mechanics
Date: 14 February 2022
URI: https://philsci-archive-dev.library.pitt.edu/id/eprint/20223

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