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Physical Review D 83 (2011) 125004
Quantum properties of a non-Gaussian state in the large-N approximation
F. Gautier, J. Serreau1

We study the properties of a non-Gaussian density matrix for an O(N) scalar field in the context of the incomplete description picture. This is of relevance for studies of decoherence and entropy production in quantum field theory. In particular, we study how the inclusion of the simplest non-Gaussian correlator in the set of measured observables modifies the effective (Gaussian) description one can infer from the knowledge of the two-point functions only. We compute exactly the matrix elements of the non-Gaussian density matrix at leading order in a 1/N expansion. This allows us to study the quantum properties (purity, entropy, coherence) of the corresponding state for arbitrarily strong non-Gaussianity. We find that if the Gaussian and the non-Gaussian observers essentially agree concerning quantum purity or correlation entropy, their conclusion can significantly differ for other, more detailed aspects such as the degree of quantum coherence of the system.
1 :  APC - UMR 7164 - AstroParticule et Cosmologie
Physique/Physique des Hautes Energies - Phénoménologie

Physique/Physique des Hautes Energies - Théorie

Physique/Physique Nucléaire Théorique

Physique/Physique Quantique
Decoherence – open systems – quantum statistical methods – Theory of quantized fields – Finite-temperature field theory – Particle-theory and field-theory models of the early Universe
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