Physics:Quantum process - Revision history

WikiHarold: Clean Quantum page image and red links

2026-05-23T23:35:34Z

Clean Quantum page image and red links

← Older revision		Revision as of 23:35, 23 May 2026
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	In [[Physics:Quantum mechanics\|quantum mechanics]], a '''quantum process''' is a somewhat ambiguous term which usually refers to the time evolution of an (~~[[Physics:Open quantum system\|~~open]]) quantum system. Under very general assumptions, a quantum process is described by the [[Physics:Quantum operation\|quantum operation]] formalism (also known as a ''quantum dynamical map''), which is a ~~[[Linear map\|~~linear]], trace-preserving, and completely positive map from the set of ~~[[Density matrix\|~~density matrices]] to itself.		In [[Physics:Quantum mechanics\|quantum mechanics]], a '''quantum process''' is a somewhat ambiguous term which usually refers to the time evolution of an (open) quantum system. Under very general assumptions, a quantum process is described by the [[Physics:Quantum operation\|quantum operation]] formalism (also known as a ''quantum dynamical map''), which is a linear, trace-preserving, and completely positive map from the set of density matrices to itself.

	For instance, in quantum process tomography, the unknown quantum process is assumed to be a quantum operation.		For instance, in quantum process tomography, the unknown quantum process is assumed to be a quantum operation.
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	[[File:~~File not found~~.~~png~~\|thumb\|280px\|~~No image available~~.]]		[[File:Quantum_process_concept_map.svg\|thumb\|280px\|process in the Quantum Collection.]]
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	[[Category:Quantum mechanics]]		[[Category:Quantum mechanics]]



	{{Sourceattribution\|Quantum process}}		{{Sourceattribution\|Quantum process}}

Harold: Add missing image fallback to Quantum header

2026-05-17T22:33:34Z

Add missing image fallback to Quantum header

← Older revision		Revision as of 22:33, 17 May 2026
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Harold: Restore Quantum article header template

2026-05-17T21:53:21Z

Restore Quantum article header template

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 {{Short description|Time evolution of quantum systems}}
 In [[Physics:Quantum mechanics|quantum mechanics]], a '''quantum process''' is a somewhat ambiguous term which usually refers to the time evolution of an ([[Physics:Open quantum system|open]]) quantum system.  Under very general assumptions, a quantum process is described by the [[Physics:Quantum operation|quantum operation]] formalism (also known as a ''quantum dynamical map''), which is a [[Linear map|linear]], trace-preserving, and completely positive map from the set of [[Density matrix|density matrices]] to itself.
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 However, not all quantum processes can be captured within the quantum operation formalism;<ref>{{cite journal|last1=Pechukas|first1=Philip|title=Reduced Dynamics Need Not Be Completely Positive|journal=Physical Review Letters|volume=73|issue=8|year=1994|pages=1060–1062|issn=0031-9007|doi=10.1103/PhysRevLett.73.1060|pmid=10057614 |bibcode=1994PhRvL..73.1060P }}</ref><ref>{{cite journal | last1=Shaji | first1=Anil | last2=Sudarshan | first2=E.C.G. | title=Who's afraid of not completely positive maps? | journal=Physics Letters A | publisher=Elsevier BV | volume=341 | issue=1–4 | year=2005 | issn=0375-9601 | doi=10.1016/j.physleta.2005.04.029 | pages=48–54| bibcode=2005PhLA..341...48S }}</ref> in principle, the density matrix of a quantum system can undergo completely arbitrary time evolution.
 == References ==

imported>WikiHarold: change

2026-01-27T13:51:24Z

change

← Older revision	Revision as of 13:51, 27 January 2026
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imported>WikiHarold: change

2026-01-27T13:51:24Z

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{{Short description|Time evolution of quantum systems}}
In [[Physics:Quantum mechanics|quantum mechanics]], a '''quantum process''' is a somewhat ambiguous term which usually refers to the time evolution of an ([[Physics:Open quantum system|open]]) quantum system. Under very general assumptions, a quantum process is described by the [[Physics:Quantum operation|quantum operation]] formalism (also known as a ''quantum dynamical map''), which is a [[Linear map|linear]], trace-preserving, and completely positive map from the set of [[Density matrix|density matrices]] to itself.

For instance, in quantum process tomography, the unknown quantum process is assumed to be a quantum operation.

However, not all quantum processes can be captured within the quantum operation formalism;<ref>{{cite journal|last1=Pechukas|first1=Philip|title=Reduced Dynamics Need Not Be Completely Positive|journal=Physical Review Letters|volume=73|issue=8|year=1994|pages=1060–1062|issn=0031-9007|doi=10.1103/PhysRevLett.73.1060|pmid=10057614 |bibcode=1994PhRvL..73.1060P }}</ref><ref>{{cite journal | last1=Shaji | first1=Anil | last2=Sudarshan | first2=E.C.G. | title=Who's afraid of not completely positive maps? | journal=Physics Letters A | publisher=Elsevier BV | volume=341 | issue=1–4 | year=2005 | issn=0375-9601 | doi=10.1016/j.physleta.2005.04.029 | pages=48–54| bibcode=2005PhLA..341...48S }}</ref> in principle, the density matrix of a quantum system can undergo completely arbitrary time evolution.

== References ==
<references/>

* {{Cite book|last1=Nielsen|first1=Michael A.|last2=Chuang|first2=Isaac L.|title=Quantum Computation and Quantum Information|publisher=Cambridge University Press|location=Cambridge|year=2010|edition=2nd|oclc=844974180|isbn=978-1-107-00217-3|title-link=Quantum Computation and Quantum Information (book)}}

[[Category:Quantum mechanics]]

{{Sourceattribution|Quantum process}}