Imprint of entanglement entropy in the power spectrum of inflationary fluctuations

Boyanovsky, D.

doi:10.1103/physrevd.98.023515

Cited by 30 publications

(24 citation statements)

References 122 publications

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“…It will be useful to formulate a Wilsonian counterpart of the out of time ordered 1-PI effective action developed in this paper. Such a Wilsonian effective theory can be extended to open quantum field theories [51,[75][76][77][78][79][80][81][82] which show up in the study of quantum cosmology and heavy ion physics. It will be interesting to determine the RG flow [51] of the OTO couplings in this Wilsonian framework to estimate their relative importance at different energy scales.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…For the purpose of analysing the constraints on the effective couplings, we find it convenient to convert their expressions (see (33),(129) , and tables 1 and 6) into integrals over a frequency domain where the integrands are determined by some spectral functions of the bath. These spectral functions are the Fourier transforms of the 4-point cumulants of O(t) as defined by the relations given in (79), (80) and (81). In these relations, we define the measure for the integral over the frequencies as…”

Section: Constraints On the Quartic Effective Couplingsmentioning

confidence: 99%

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Out of time ordered effective dynamics of a quartic oscillator

Chakrabarty

Chaudhuri

2019

SciPost Phys.

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We study the dynamics of a quantum Brownian particle weakly coupled to a thermal bath. Working in the Schwinger-Keldysh formalism, we develop an effective action of the particle up to quartic terms. We demonstrate that this quartic effective theory is dual to a stochastic dynamics governed by a non-linear Langevin equation. The Schwinger-Keldysh effective theory, or the equivalent non-linear Langevin dynamics, is insufficient to determine the out of time order correlators (OTOCs) of the particle. To overcome this limitation, we construct an extended effective action in a generalised Schwinger-Keldysh framework. We determine the additional quartic couplings in this OTO effective action and show their dependence on the bath's 4-point OTOCs. We analyse the constraints imposed on the OTO effective theory by microscopic reversibility and thermality of the bath. We show that these constraints lead to a generalised fluctuation-dissipation relation between the non-Gaussianity in the distribution of the thermal noise experienced by the particle and the thermal jitter in its damping coefficient. The quartic effective theory developed in this work provides extension of several results previously obtained for the cubic OTO dynamics of a Brownian particle. Contents SciPost PhysicsSubmission [22,[27][28][29]. Nevertheless, it is interesting to explore the corrections to this effective dynamics by including the cubic and higher degree terms in the analysis. A simple way to obtain such corrections is to extend the Caldeira-Leggett model by introducing a non-linear combination of the bath oscillators' positions in the operator that couples to the particle [29,30].One such extension was discussed in [30] where the oscillators in the bath were divided into two sets (labelled by X and Y). Then apart from the bilinear interactions (which are present in the Caldeira-Leggett model), small cubic interactions were introduced between the particle (q) and pairs of bath oscillators. Each such pair consisted of one oscillator drawn from the set X and the other from the set Y. Due to these cubic interactions, this model was called the 'qXY model'.Introduction of these cubic interactions leads to cubic and higher degree terms in the effective action of the particle. In [30], this effective theory was studied up to the cubic terms in a Markovian limit. It was shown to be dual to a non-linear Langevin dynamics which has perturbative corrections over the linear Langevin dynamics in the Caldeira-Leggett model. The additional parameters in this non-linear dynamics receive contributions from the 3-point correlators of the bath. These 3-point correlators lead to an anharmonicity in the particle's dynamics and a non-Gaussianity in the distribution of the thermal noise experienced by the particle. In addition, they also give rise to thermal jitters 1 in both the frequency and the damping of the particle. The thermal jitter in the damping coefficient and the non-Gaussianity in the noise are connected by a generalised fluctuation-dissipation relation [30...

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Section: Conclusion and Discussionmentioning

confidence: 99%

Section: Constraints On the Quartic Effective Couplingsmentioning

confidence: 99%

Out of time ordered effective dynamics of a quartic oscillator

Chakrabarty

Chaudhuri

2019

SciPost Phys.

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“…In fact, there have been several attempts to do precisely that [26,27,30,31,47]. In addition, a lot of work has been invested into a much easier set of problems, namely into studying how the inflaton coupling with the other quantum fields (scalar, fermionic or vector) induces decoherence in the inflaton sector [16,18,31,34]. While the earlier works considered simple models with bilinear couplings [16,18] (since these couplings are non-dissipative, they are not true interactions), more recent works studied true interactions [31,34].…”

Section: Growing Curvature Momentum From Quantum Interactionsmentioning

confidence: 99%

“…While early works [11][12][13][14][15][16][17][18] used the late time observer's inability to get a complete access to the state of cosmological perturbations as the principal source of decoherence and classicalization (the so-called 'decoherence without decoherence'), later works used more realistic settings, in which (dissipative) interactions among quantum fields during (or after) inflation is the principal cause for decoherence. The interactions considered range from self-interactions of the inflaton field [24][25][26][27], interactions with gravitational waves [28,29], interactions with other scalar fields [30][31][32][33], as well as interactions with massive fermionic fields [34].…”

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confidence: 99%

Entropy production in inflation from spectator loops

Friedrich

Prokopec

2019

Phys. Rev. D

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Perturbations in cosmic microwave background (CMB) photons and large scale structure of the universe are sourced primarily by the curvature perturbation which is widely believed to be produced during inflation. In this paper we present a 2-field inflationary model in which the inflaton couples bi-quadratically to a spectator field. We show that the spectator induces a rapid growth of the momentum of the curvature perturbation and the associated Gaussian van Neumann entropy during inflation such that the initial conditions at the end of inflation are substantially different from the standard ones. Consequently, one ought to reconsider the kinetic equations describing evolution of the photon, dark matter and baryonic fluids in radiation and matter eras and take account of the fact that the curvature perturbation and its canonical momentum are two a priory independent stochastic fields. We also briefly analyze possible imprints on the CMB temperature fluctuations from the more general inflationary scenario which contains light spectator fields coupled to the inflaton. * Electronic address: p.friedrich@uu.nl ‡ Electronic address: t.prokopec@uu.nl

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“…The Feynman-Vernon influence functional and similar field-theoretic approaches have been used previously, e.g., in studies of quantum Brownian motion [56,57], interacting quantum field theories (both in vacuum [58] and at finite temperature [59]) and decoherence during inflation in the early Universe [60][61][62][63][64][65][66] (see also Refs. [67][68][69][70] for the Hamiltonian approach), as well as quarkonium suppression in heavy-ion collisions [71,72].…”

Section: Introductionmentioning

confidence: 99%

Open quantum dynamics induced by light scalar fields

et al. 2019

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We consider the impact of a weakly coupled environment comprising a light scalar field on the open dynamics of a quantum probe field, resulting in a master equation for the probe field that features corrections to the coherent dynamics, as well as decoherence and momentum diffusion. The light scalar is assumed to couple to matter either through a nonminimal coupling to gravity or, equivalently, through a Higgs portal.Motivated by applications to experiments such as atom interferometry, we assume that the probe field can be initialized, by means of external driving, in a state that is not an eigenstate of the light scalar-field-probe system, and we derive the master equation for single-particle matrix elements of the reduced density operator of a toy model. We comment on the possibilities for experimental detection and the related challenges, and highlight possible pathways for further improvements. This derivation of the master equation requires techniques of non-equilibrium quantum field theory, including the Feynman-Vernon influence functional and thermo field dynamics, used to motivate a method of Lehmann-Symanzik-Zimmermann-like reduction. In order to obtain cutoff-independent results for the probe-field dynamics, we find that it is necessary to use a time-dependent renormalization procedure. Specifically, we show that non-Markovian effects following a quench, namely the violation of time-translational invariance due to finite-time effects, lead to a timedependent modulation of the usual vacuum counterterms.

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Imprint of entanglement entropy in the power spectrum of inflationary fluctuations

Cited by 30 publications

References 122 publications

Out of time ordered effective dynamics of a quartic oscillator

Out of time ordered effective dynamics of a quartic oscillator

Entropy production in inflation from spectator loops

Open quantum dynamics induced by light scalar fields

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