Quantum states of the bouncing universe

2013
journal article
article
cris.lastimport.wos2024-04-09T21:10:43Z
dc.abstract.enIn this paper we study quantum dynamics of the bouncing cosmological model. We focus on the model of the flat Friedmann-Robertson-Walker universe with a free scalar field. The bouncing behavior, which replaces the classical singularity, appears due to the modification of general relativity using the methods of loop quantum cosmology. We show that there exists a unitary transformation that enables one to describe the system as a free particle with a Hamiltonian equal to the canonical momentum. We examine properties of the various quantum states of the universe: the boxcar state, the standard coherent state, and the soliton-like state, as well as Schrödinger’s cat states constructed from these states. Characteristics of the states—such as quantum moments and Wigner functions—are investigated. We show that each of these states have, for some range of parameters, a proper semiclassical limit fulfilling the correspondence principle. The decoherence of the superposition of two universes is described and possible interpretations in terms of triad orientation and the Belinsky-Khalatnikov-Lifshitz conjecture are given. We also examine negative-part sectors of the Wigner functions for the considered states. Their respective areas and localizations in the phase space feature an adequate estimate of nonclassicality. In particular, we show that regions where the Wigner function for the Glauber coherent cat state assumes its negative values have area equal to one fourth of the Planck constant. Based on the examined examples, we also conjecture that regions with negative values for the Wigner function are never smaller than one fourth of the Planck constant for states satisfying the uncertainty principle.pl
dc.affiliationWydział Fizyki, Astronomii i Informatyki Stosowanej : Instytut Fizyki im. Mariana Smoluchowskiegopl
dc.contributor.authorGazeau, Jean Pierrepl
dc.contributor.authorMielczarek, Jakub - 103621 pl
dc.contributor.authorPiechocki, Włodzimierzpl
dc.date.accessioned2015-06-30T14:44:30Z
dc.date.available2015-06-30T14:44:30Z
dc.date.issued2013pl
dc.description.number12pl
dc.description.publication1pl
dc.description.volume87pl
dc.identifier.articleid123508pl
dc.identifier.doi10.1103/PhysRevD.87.123508pl
dc.identifier.eissn1550-2368pl
dc.identifier.issn1550-7998pl
dc.identifier.urihttp://ruj.uj.edu.pl/xmlui/handle/item/10821
dc.languageengpl
dc.language.containerengpl
dc.rightsDodaję tylko opis bibliograficzny*
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dc.subtypeArticlepl
dc.titleQuantum states of the bouncing universepl
dc.title.journalPhysical Review. D, Particles, Fields, Gravitation, and Cosmologypl
dc.typeJournalArticlepl
dspace.entity.typePublication
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