Quantum reversibility is relative, or does a quantum measurement reset initial conditions?
I compare the role of the information in classical and quantum dynamics by examining the relation between information flows in measurements and the ability of observers to reverse evolutions. I show that in the Newtonian dynamics reversibility is unaffected by the observer's retention of the in...
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Published in | Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences Vol. 376; no. 2123; p. 20170315 |
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Main Author | |
Format | Journal Article |
Language | English |
Published |
England
The Royal Society Publishing
13.07.2018
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Subjects | |
Online Access | Get full text |
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Summary: | I compare the role of the information in classical and quantum dynamics by examining the relation between information flows in measurements and the ability of observers to reverse evolutions. I show that in the Newtonian dynamics reversibility is unaffected by the observer's retention of the information about the measurement outcome. By contrast-even though quantum dynamics is unitary, hence, reversible-reversing quantum evolution that led to a measurement becomes, in principle, impossible for an observer who keeps the record of its outcome. Thus, quantum irreversibility can result from the information gain rather than just its loss-rather than just an increase of the (von Neumann) entropy. Recording of the outcome of the measurement resets, in effect, initial conditions within the observer's (branch of) the Universe. Nevertheless, I also show that the observer's friend-an agent who knows what measurement was successfully carried out and can confirm that the observer knows the outcome but resists his curiosity and does not find out the result-can, in principle, undo the measurement. This relativity of quantum reversibility sheds new light on the origin of the arrow of time and elucidates the role of information in classical and quantum physics. Quantum discord appears as a natural measure of the extent to which dissemination of information about the outcome affects the ability to reverse the measurement.
This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'. |
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Bibliography: | Discussion meeting issue ‘Foundations of quantum mechanics and their impact on contemporary society’ compiled and edited by Gerardo Adesso, Rosario Lo Franco and Valentina Parigi ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 USDOE Laboratory Directed Research and Development (LDRD) Program LA-UR-18-22300 AC52-06NA25396 One contribution of 17 to a discussion meeting issue ‘Foundations of quantum mechanics and their impact on contemporary society’. |
ISSN: | 1364-503X 1471-2962 |
DOI: | 10.1098/rsta.2017.0315 |