Reduced density matrices and decoherence in quantum cosmology

Journal Article · Wed May 15 04:00:00 EDT 1991 · Physical Review, D (Particles Fields); (USA)

DOI:https://doi.org/10.1103/PhysRevD.43.3317· OSTI ID:5661739

Laflamme, R ^[1]; Louko, J ^[2]

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1. Department of Physics, University of British Columbia, 6224 Agriculture Road, Vancouver, British Columbia, Canada V6T2A6 (CA) Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB39EW, United Kingdom (GB)
2. Theoretical Physics Institute, Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G2J1 (CA)

We investigate a quantum cosmological model consisting of inhomogeneous massless minimally coupled scalar field perturbations on a closed Friedmann-Robertson-Walker minisuperspace model with a spatially homogeneous massless minimally coupled scalar field. We discuss how to define a reduced density matrix by summing over the perturbations in the full density matrix, using the approximate Hilbert-space structure that exists for the perturbation wave function when the minisuperspace part of the wave function is of the WKB form. We then concentrate on two particular candidates for a reduced density matrix and discuss their relation to particle creation effects in quantum field theory on curved spacetime. Our results do not suggest that decoherence in the reduced density matrices could be directly identified as a lack of interference between the classical trajectories that correspond to a WKB minisuperspace part of the total wave function.

• OSTI ID: 5661739
• Journal Information: Physical Review, D (Particles Fields); (USA), Journal Name: Physical Review, D (Particles Fields); (USA) Journal Issue: 10 Vol. 43:10; ISSN PRVDA; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

657002* -- Theoretical & Mathematical Physics-- Classical & Quantum Mechanics
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMOLOGICAL MODELS
DENSITY MATRIX
DIFFERENTIAL EQUATIONS
EQUATIONS
FIELD THEORIES
FUNCTIONS
HAMILTON-JACOBI EQUATIONS
MATHEMATICAL MODELS
MATRICES
PARTIAL DIFFERENTIAL EQUATIONS
PERTURBATION THEORY
QUANTUM FIELD THEORY
SCALAR FIELDS
WAVE FUNCTIONS
WKB APPROXIMATION