Generation of squeezed radiation from vacuum in the cosmos and the laboratory

Grishchuk, L. P.; Haus, H. A.; Bergman, K.

doi:10.1103/physrevd.46.1440

Cited by 60 publications

(71 citation statements)

References 20 publications

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“…u in eq. (2.9) is generally incorporated into the frequency term by using the conformal time variable η [6,7,8]; such a computational strategy is very useful in the phenomenological approach, however our purpose in this paper is to illustrate the subtleties of the canonical quantization for non-unitary time evolution and therefore we must explicitly take care of such a term in eq. (2.9).…”

Section: Expanding Universementioning

confidence: 99%

“…a(t) a(t) (the Hubble constant), is adopted, h µν may be still decomposed into partial waves as in (2.5); however, in such a case one obtains the equation [1,6,7,8] (see also [31] ..…”

Section: Expanding Universementioning

confidence: 99%

“…and it turns out to be convenient to introduce the variables U and V by the transformations 8) which preserve the commutation relations (3.7):…”

Section: Quantization In Expanding Geometrymentioning

confidence: 99%

“…The particle production in a gravitational field [4], the Hawking radiation [5] and the generation of gravitational waves from vacuum in an expanding Universe [6,7,8] are indeed strictly related with the problem of properly defining the particle number operator in curved space-time (see also [9] and [10,11]). …”

Section: Introductionmentioning

confidence: 99%

“…The emerging picture of the canonical quantization scheme we obtain is thus a unified view of many features of time evolution in expanding geometry, including coherence, two-mode squeezing, entropy and vacuum thermal properties [6,7,8,27,28,29].…”

Section: Introductionmentioning

confidence: 99%

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Vacuum structure for expanding geometry

Alfinito

Mańka²,

Vitiello

1999

Class. Quantum Grav.

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We consider gravitational wave modes in the FRW metrics in a de Sitter phase and show that the state space splits into many unitarily inequivalent representations of the canonical commutation relations. Non-unitary time evolution is described as a trajectory in the space of the representations. The generator of time evolution is related to the entropy operator. The thermodynamic arrow of time is shown to point in the same direction of the cosmological arrow of time. The vacuum is a two-mode SU(1,1) squeezed state of thermo field dynamics. The link between expanding geometry, squeezing and thermal properties is exhibited.

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Section: Expanding Universementioning

confidence: 99%

“…a(t) a(t) (the Hubble constant), is adopted, h µν may be still decomposed into partial waves as in (2.5); however, in such a case one obtains the equation [1,6,7,8] (see also [31] ..…”

Section: Expanding Universementioning

confidence: 99%

“…and it turns out to be convenient to introduce the variables U and V by the transformations 8) which preserve the commutation relations (3.7):…”

Section: Quantization In Expanding Geometrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Vacuum structure for expanding geometry

Alfinito

Mańka²,

Vitiello

1999

Class. Quantum Grav.

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Four‐mode Squeezed States in de Sitter Space: A Study With Two Field Interacting Quantum System

Choudhury

Panda

Pandey

et al. 2022

Fortschritte der Physik

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In this paper we study the application of four-mode squeezed states in the cosmological context, studying two weakly coupled scalar fields in the planar patch of the de Sitter space. We construct the four-mode squeezed state formalism and connect this concept with the Hamiltonian of the two coupled inverted harmonic oscillators having a time-dependent effective frequency in the planar patch of the de Sitter space. Further, the corresponding evolution operator for the quantum Euclidean vacuum state has been constructed, which captures its dynamics. Using the Heisenberg picture coupled differential equations describing the time evolution for all squeezing parameters (amplitude, phase and angle) have been obtained, for the weakly coupled two scalar field model. With the help of these evolutions for the coupled system, we simulate the dynamics of the squeezing parameters in terms of conformal time. From our analysis, we observe interesting dynamics, which helps us to explore various underlying physical implications of the weakly coupled two scalar field system in the planar patch of the de Sitter cosmological background.

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C${\cal C}$osmological K${\cal K}$rylov C${\cal C}$omplexity

Adhikari

Choudhury

2022

Fortschritte der Physik

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In this paper, we study the Krylov complexity (K) from the planar/inflationary patch of the de Sitter space using the two mode squeezed state formalism in the presence of an effective field having sound speed c s . From our analysis, we obtain the explicit behavior of Krylov complexity (K) and lancoz coefficients (b n ) with respect to the conformal time scale and scale factor in the presence of effective sound speed c s . Since lancoz coefficients (b n ) grow linearly with integer n, this suggests that universe acts like a chaotic system during this period. We also obtain the corresponding Lyapunov exponent 𝝀 in presence of effective sound speed c s . We show that the Krylov complexity (K) for this system is equal to average particle numbers suggesting it's relation to the volume. Finally, we give a comparison of Krylov complexity (K) with entanglement entropy (Von-Neumann) where we found that there is a large difference between Krylov complexity (K) and entanglement entropy for large values of squeezing amplitude. This suggests that Krylov complexity (K) can be a significant probe for studying the dynamics of the cosmological system even after the saturation of entanglement entropy.

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Generation of squeezed radiation from vacuum in the cosmos and the laboratory

Cited by 60 publications

References 20 publications

Vacuum structure for expanding geometry

Vacuum structure for expanding geometry

Four‐mode Squeezed States in de Sitter Space: A Study With Two Field Interacting Quantum System

C${\cal C}$osmological K${\cal K}$rylov C${\cal C}$omplexity

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