Why protective measurement does not establish the reality of the quantum state

Combes, J; Ferrie, C; Leifer, MS; Pusey, MF

Why protective measurement does not establish the reality of the quantum state

Combes, J Ferrie, C

Leifer, MS Pusey, MF

Permalink

Publisher:: Springer Science and Business Media LLC
Publication Type:: Journal Article
Citation:: Quantum Studies: Mathematics and Foundations, 2018, 5, (2), pp. 189-211
Issue Date:: 2018-06-01

Closed Access

	Filename	Description	Size
	s40509-017-0111-4.pdf	Published version	729.6 kB	Adobe PDF	View/Open

Copyright Clearance Process

Recently Added
In Progress
Closed Access

This item is closed access and not available.

Full metadata record

Field	Value	Language
dc.contributor.author	Combes, J
dc.contributor.author	Ferrie, C https://orcid.org/0000-0003-2736-9943
dc.contributor.author	Leifer, MS
dc.contributor.author	Pusey, MF
dc.date.accessioned	2022-08-27T05:44:05Z
dc.date.available	2022-08-27T05:44:05Z
dc.date.issued	2018-06-01
dc.identifier.citation	Quantum Studies: Mathematics and Foundations, 2018, 5, (2), pp. 189-211
dc.identifier.issn	2196-5609
dc.identifier.issn	2196-5617
dc.identifier.uri	http://hdl.handle.net/10453/160931
dc.description.abstract	“Protective measurement” refers to two related schemes for finding the expectation value of an observable without disturbing the state of a quantum system, given a single copy of the system that is subject to a “protecting” operation. There have been several claims that these schemes support interpreting the quantum state as an objective property of a single quantum system. Here we provide three counter-arguments, each of which we present in two versions tailored to the two different schemes. Our first argument shows that the same resources used in protective measurement can be used to reconstruct the quantum state in a different way via process tomography. Our second argument is based on exact analyses of special cases of protective measurement, and our final argument is to construct explicit “ψ-epistemic” toy models for protective measurement, which strongly suggest that protective measurement does not imply the reality of the quantum state. The common theme of the three arguments is that almost all of the information comes from the “protection” operation rather than the quantum state of the system, and hence the schemes have no implications for the reality of the quantum state.
dc.language	en
dc.publisher	Springer Science and Business Media LLC
dc.relation.ispartof	Quantum Studies: Mathematics and Foundations
dc.relation.isbasedon	10.1007/s40509-017-0111-4
dc.rights	info:eu-repo/semantics/closedAccess
dc.title	Why protective measurement does not establish the reality of the quantum state
dc.type	Journal Article
utslib.citation.volume	5
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Strength - QSI - Centre for Quantum Software and Information
utslib.copyright.status	closed_access	*
dc.date.updated	2022-08-27T05:44:04Z
pubs.issue	2
pubs.publication-status	Published
pubs.volume	5
utslib.citation.issue	2

Abstract:

“Protective measurement” refers to two related schemes for finding the expectation value of an observable without disturbing the state of a quantum system, given a single copy of the system that is subject to a “protecting” operation. There have been several claims that these schemes support interpreting the quantum state as an objective property of a single quantum system. Here we provide three counter-arguments, each of which we present in two versions tailored to the two different schemes. Our first argument shows that the same resources used in protective measurement can be used to reconstruct the quantum state in a different way via process tomography. Our second argument is based on exact analyses of special cases of protective measurement, and our final argument is to construct explicit “ψ-epistemic” toy models for protective measurement, which strongly suggest that protective measurement does not imply the reality of the quantum state. The common theme of the three arguments is that almost all of the information comes from the “protection” operation rather than the quantum state of the system, and hence the schemes have no implications for the reality of the quantum state.

Please use this identifier to cite or link to this item:

http://hdl.handle.net/10453/160931