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Weak values and the past of a quantum particle

Lookup NU author(s): Dr Jonte HanceORCiD

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Abstract

We investigate four key issues with using a nonzero weak value of the spatial projection operator to infer the past path of an individual quantum particle. First, we note that weak measurements disturb a system, so any approach relying on such a perturbation to determine the location of a quantum particle describes the state of a disturbed system, not that of a hypothetical undisturbed system. Second, even assuming no disturbance, there is no reason to associate the nonzero weak value of an operator containing the spatial projection operator with the classical idea of “particle presence.” Third, weak values are only measurable over ensembles, and so to infer properties of individual particles from values of them is problematic. Finally, weak value approaches to the path of a particle do not provide information beyond standard quantum mechanics (and the classical modes supporting the experiment). We know of no experiment with testable consequences that demonstrates a connection between particle presence and weak values.

Publication metadata

Author(s): Hance JR, Rarity J, Ladyman J

Publication type: Article

Publication status: Published

Journal: Physical Review Research

Year: 2023

Volume: 5

Issue: 2

Online publication date: 21/04/2023

Acceptance date: 21/12/2022

Date deposited: 08/04/2024

ISSN (electronic): 2643-1564

Publisher: American Physical Society

URL: https://doi.org/10.1103/PhysRevResearch.5.023048

DOI: 10.1103/PhysRevResearch.5.023048

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