Wave function collapse: Difference between revisions

Revision as of 16:55, 23 March 2025

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{{Use American English|date=January 2019}}

{{Quantum mechanics}}

In various [[Interpretations of quantum mechanics|interpretations]] of [[quantum mechanics]], '''wave function collapse''', also called '''reduction of the state vector''',<ref>{{Cite journal |last=Penrose |first=Roger |date=May 1996 |title=On Gravity's role in Quantum State Reduction |url=http://link.springer.com/10.1007/BF02105068 |journal=General Relativity and Gravitation |language=en |volume=28 |issue=5 |pages=581–600 |doi=10.1007/BF02105068 |issn=0001-7701}}</ref> occurs when a [[wave function]]—initially in a [[quantum superposition|superposition]] of several [[eigenstates]]—reduces to a single eigenstate due to [[Fundamental interaction|interaction]] with the external world. This interaction is called an [[Observation (physics)|''observation'']] and is the essence of a [[measurement in quantum mechanics]], which connects the wave function with classical [[observable]]s such as [[position (vector)|position]] and [[momentum]]. Collapse is one of the two processes by which [[quantum system]]s evolve in time; the other is the continuous evolution governed by the [[Schrödinger equation]].<ref name="Grundlagen">

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|author=J. von Neumann

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WhileIn standardthe quantum[[Copenhagen mechanics postulatesinterpretation]], wave function collapse to connectconnects quantum to classical models, somewith extensiona theoriesspecial propose[[Copenhagen physicalinterpretation#Role processesof thatthe causeobserver|role collapsefor the observer]]. TheBy contrast, [[Objective-collapse theory|objective-collapse]] proposes an origin in depthphysical studyprocesses. ofIn the [[quantummany-worlds decoherenceinterpretation]], hascollapse proposeddoes thatnot collapseexist; isall relatedwave tofunction theoutcomes interactionoccur of awhile [[quantum systemdecoherence]] withaccounts itsfor environmentthe appearance of collapse.

Historically, [[Werner Heisenberg]] was the first to use the idea of wave function reduction to explain quantum measurement.<ref>[[Werner Heisenberg|Heisenberg, W.]] (1927). Über den anschaulichen Inhalt der quantentheoretischen Kinematik und Mechanik, ''Z. Phys.'' '''43''': 172–198. Translation as [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19840008978.pdf "The actual content of quantum theoretical kinematics and mechanics"].</ref><ref name="C. Kiefer-2002" />