Kabel, Viktoria and de la Hamette, Anne-Catherine and Apadula, Luca and Cepollaro, Carlo and Gomes, Henrique and Butterfield, Jeremy and Brukner, Caslav (2025) Identification is Pointless: Quantum Reference Frames, Localisation of Events, and the Quantum Hole Argument. Nature Communications Physics, 8. p. 185.

Text KabelDeLaHametteEtAl.IndentifnPointlessPublished.2402.10267v2ForPittArchive.pdf Download (2MB)

Abstract

The study of quantum reference frames (QRFs) is motivated by the idea of taking into account the quantum properties of the reference frames used, explicitly or implicitly, in our description of physical systems. Like classical reference frames, QRFs can be used to define physical quantities relationally. Unlike their classical analogue, they relativise the notions of superposition and entanglement. Here, we explain this feature by examining how configurations or locations are identified across different branches in superposition. We show that, in the presence of symmetries, whether a system is in “the same” or “different” configurations across the branches depends on the choice of QRF. Hence, sameness and difference — and thus superposition and entanglement — lose their absolute meaning. We apply these ideas to the context of semi-classical spacetimes in superposition and use coincidences of four scalar fields to construct a comparison map between spacetime points in the different branches. This reveals that the localisation of an event is frame-dependent. We discuss the implications for indefinite causal order and the locality of interaction and conclude with a generalisation of Einstein’s hole argument to the quantum context.

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Item Type:	Published Article or Volume
Creators:	Creators Email ORCID Kabel, Viktoria viktoria.kabel@gmail.com 0000-0002-0776-3612 de la Hamette, Anne-Catherine acdelahamette@gmail.com 0000-0003-4811-822X Apadula, Luca Luca.Apadula@oeaw.ac.at 0009-0001-5488-2171 Cepollaro, Carlo Carlo.Cepollaro@oeaw.ac.at 0000-0001-6762-8159 Gomes, Henrique gomes.ha@gmail.com 0000-0002-9285-0090 Butterfield, Jeremy jb56@cam.ac.uk 0000-0002-0215-5802 Brukner, Caslav caslav.brukner@univie.ac.at 0000-0002-6549-5863
Keywords:	Reference frames, quantum reference frame, fibre bundle formulation of a theory’s space of models, counterpart theory, superposition of spacetimes, hole argument, quantum hole argument, quantum event, localisation of events.
Subjects:	General Issues > Determinism/Indeterminism Specific Sciences > Physics > Quantum Gravity Specific Sciences > Physics > Quantum Mechanics Specific Sciences > Physics > Relativity Theory Specific Sciences > Physics > Symmetries/Invariances
Depositing User:	Jeremy Butterfield
Date Deposited:	30 Apr 2025 14:08
Last Modified:	02 May 2025 13:30
Item ID:	25211
Journal or Publication Title:	Nature Communications Physics
Publisher:	Sprnger Nature
Official URL:	https://doi.org/10.1038/s42005-025-02084-3
DOI or Unique Handle:	10.1038/s42005-025-02084-3
Subjects:	General Issues > Determinism/Indeterminism Specific Sciences > Physics > Quantum Gravity Specific Sciences > Physics > Quantum Mechanics Specific Sciences > Physics > Relativity Theory Specific Sciences > Physics > Symmetries/Invariances
Date:	30 April 2025
Page Range:	p. 185
Volume:	8
URI:	https://philsci-archive.pitt.edu/id/eprint/25211

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• Identification is Pointless: Quantum Reference Frames, Localisation of Events, and the Quantum Hole Argument. (deposited 20 Feb 2024 21:46)
  • Identification is Pointless: Quantum Reference Frames, Localisation of Events, and the Quantum Hole Argument. (deposited 30 Apr 2025 14:08) [Currently Displayed]

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