Density matrix formalism for interacting quantum fields

Abstract

We provide a description of interacting quantum fields in terms of density matrices for any occupation numbers in Fock space in a momentum basis. As a simple example, we focus on a real scalar field interacting with another real scalar field, and present a practicable formalism for directly computing the density matrix elements of the combined scalar-scalar system. For deriving the main formula, we use techniques from non-equilibrium quantum field theory like thermo field dynamics and the Schwinger-Keldysh formalism. Our results allow for studies of particle creation/annihilation processes at finite times and other non-equilibrium processes including those found in the theory of open quantum systems.

21 pages, 7 figures, as published in Universe. arXiv admin note: text overlap with arXiv:2204.08829

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Cited by in corpus (6)

• In-in formalism for the entropy of quantum fields in curved spacetimes
• Dilaton-induced open quantum dynamics
• An Open Effective Field Theory for light in a medium
• Reduced Density Matrices and Phase-Space Distributions in Thermofield Dynamics
• Effective field theory of particle mixing
• Particles in finite volumes and a toy model of decaying neutrons