Classical Perturbations From Decoherence of Quantum Fluctuations in the Inflationary Universe

Brandenberger, Robert H.; Laflamme, Raymond; Mijic, Milan

doi:10.1142/s0217732390002651

Cited by 79 publications

(83 citation statements)

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“…In addition to the atomic physics, quantum optics, and quantum information processing (which were all mentioned throughout this review) it stretches from material sciences (Karlsson, 1998;Dreismann, 2000), surface science, where it seems to be an essential ingredient explaining emission of electrons (Brodie, 1995;Durakiewicz et al, 2001) through heavy ion collisions (Krzywicki, 1993) to quantum gravity and cosmology (Zeh, 1986(Zeh, , 1988(Zeh, , 1992Kiefer, 1987;Kiefer and Zeh, 1995;Halliwell, 1989; Brandenberger, Laflamme and Mijic, 1990; Kamenshchik, 1990, 1995;Paz andSinha, 1991, 1992;Castagnino et al, 1993, Mensky andNovikov, 1996).…”

Section: Discussionmentioning

confidence: 99%

Decoherence, einselection, and the quantum origins of the classical

2003

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Decoherence is caused by the interaction with the environment which in effect monitors certain observables of the system, destroying coherence between the pointer states corresponding to their eigenvalues. This leads to environment-induced superselection or einselection, a quantum process associated with selective loss of information. Einselected pointer states are stable. They can retain correlations with the rest of the Universe in spite of the environment. Einselection enforces classicality by imposing an effective ban on the vast majority of the Hilbert space, eliminating especially the flagrantly nonlocal "Schrödinger cat" states. Classical structure of phase space emerges from the quantum Hilbert space in the appropriate macroscopic limit: Combination of einselection with dynamics leads to the idealizations of a point and of a classical trajectory. In measurements, einselection replaces quantum entanglement between the apparatus and the measured system with the classical correlation. Only the preferred pointer observable of the apparatus can store information that has predictive power. When the measured quantum system is microscopic and isolated, this restriction on the predictive utility of its correlations with the macroscopic apparatus results in the effective "collapse of the wavepacket". Existential interpretation implied by einselection regards observers as open quantum systems, distinguished only by their ability to acquire, store, and process information. Spreading of the correlations with the effectively classical pointer states throughout the environment allows one to understand 'classical reality' as a property based on the relatively objective existence of the einselected states: They can be "found out" without being re-prepared, e.g, by intercepting the information already present in the environment. The redundancy of the records of pointer states in the environment (which can be thought of as their 'fitness' in the Darwinian sense) is a measure of their classicality. A new symmetry appears in this setting: Environment -assisted invariance or envariance sheds a new light on the nature of ignorance of the state of the system due to quantum correlations with the environment, and leads to Born's rules and to the reduced density matrices, ultimately justifying basic principles of the program of decoherence and einselection.

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Section: Discussionmentioning

confidence: 99%

Decoherence, einselection, and the quantum origins of the classical

2003

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“…Various arguments and calculations suggesting that a form of such environmental decoherence can indeed occur for inflationary perturbations have been put forward in [8,9,10,11,12,13,14,15,16]. In [9,10,11,12,13,14,16], the environment is taken to consist of the short wavelength modes which are coupled to the long wavelength modes via non-linear couplings.…”

Section: Introductionmentioning

confidence: 99%

Decoherence from isocurvature perturbations in inflation

Prokopec

Rigopoulos²

2007

J. Cosmol. Astropart. Phys.

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We discuss the possible role of isocurvature perturbations for the quantum decoherence of the curvature perturbation during inflation. We point out that if the inflaton trajectory in field space is curved, the adiabatic mode is generically coupled to the isocurvature mode and thus tracing out the latter can cause the curvature perturbation to decohere. We explicitly investigate this suggestion in a model of inflation with two decoupled massive fields and find that decoherence is effective for a wide range of mass ratios. In particular, we calculate the entanglement entropy for this model and show that it grows after horizon exit, providing a quantitative measure for decoherence.

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“…This directly implies that due to this serious drawback in the underlying structural setup it is not at all possible to set up a Bell inequality violating experimental setup in the context of cosmology. But to make a further strong conclusive statement regarding this issue one needs to investigate the decoherence effect and its impact in cosmological observation [10][11][12][13][14][15][16][17][18][19]. If the cosmological observables satisfy the basic requirements of the decoherence effect then it is possible to perform measurements from two exactly commuting cosmological observables and this can enable one to design a Bell inequality violating cosmological experimental setup.…”

Section: Is To Me So Great An Absurdity That I Believe No Man Who mentioning

confidence: 99%

“…Gravitational waves [7][8][9][10][12][13][14][15][16][17][18][19][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] More generically, such interactions with the additional environment can be expressed in FLRW background as…”

Section: Setup For the Cosmological Bell Violating Experimentsmentioning

confidence: 99%

Bell violation in the sky

2017

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In this work, we have studied the possibility of setting up Bell's inequality violating experiment in the context of cosmology, based on the basic principles of quantum mechanics. First we start with the physical motivation of implementing the Bell inequality violation in the context of cosmology. Then to set up the cosmological Bell violating test experiment we introduce a model independent theoretical framework using which we have studied the creation of new massive particles by implementing the WKB approximation method for the scalar fluctuations in the presence of additional time-dependent mass contribution in the cosmological perturbation theory. Here for completeness we compute the total number density and the energy density of the newly created particles in terms of the Bogoliubov coefficients using the WKB approximation method. Next using the background scalar fluctuation in the presence of a new time-dependent mass contribution, we explicitly compute the expression for the one point and two point correlation functions. Furthermore, using the results for a one point function we introduce a new theoretical cosmological parameter which can be expressed in terms of the other known inflationary observables and can also be treated as a future theoretical probe to break the degeneracy amongst various models of inflation. Additionally, we also fix the scale of inflation in a model-independent way without any prior knowledge of primordial gravitational waves. Also using the input from a newly introduced cosmological parameter, we finally give a theoretical estimate for the tensor-to-scalar ratio in a modelindependent way. Next, we also comment on the technicalities of measurements from isospin breaking interactions and the future prospects of newly introduced massive particles in a cosmological Bell violating test experiment. Further, we a

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Classical Perturbations From Decoherence of Quantum Fluctuations in the Inflationary Universe

Cited by 79 publications

References 0 publications

Decoherence, einselection, and the quantum origins of the classical

Decoherence, einselection, and the quantum origins of the classical

Decoherence from isocurvature perturbations in inflation

Bell violation in the sky

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