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Schwinger-Keldysh nonperturbative field theory of open quantum systems beyond the Markovian regime: Application to spin-boson and spin-chain-boson models by Reyes-Osorio, Felipe; Garcia-Gaitan, Federico; Strachan, David J.; Plechac, Petr; Clark, Stephen R.; Nikolic, Branislav K. is a scholarly article available to read on EtoBox.

What is Schwinger-Keldysh nonperturbative field theory of open quantum systems beyond the Markovian regime: Application to spin-boson and spin-chain-boson models about?

Open quantum systems with many interacting degrees of freedom pose a formidable challenge for presently available theoretical methods, especially when dissipative environment imposes non-Markovian dynamics on them with memory effects and revival of genuine quantum properties. Even the archetypical spin-boson model, where a single spin-1/2 interacts with an infinite bosonic bath, requires switching between methods for different choice of system and bath parameters. Here, we construct a field-theoretic framework as a single methodology that can handle many mutually interacting quantum spins of arbitrary value S, spatial dimensionality, system-bath coupling, bath temperature and spectral properties of the bath. Our framework combines Schwinger-Keldysh field theory (SKFT) with two-particle irreducible (2PI) action resumming a class of Feynman diagrams to an infinite order originating from 1/N expansion, where N is the number of Schwinger bosons to which the spin is mapped. Remarkably, the SKFT+2PI approach closely tracks numerically exact benchmarks for spin-boson in the non-Markovian regime obtained from hierarchical equations of motion or tensor network methods. Furthermore, we demon

Author

Reyes-Osorio, Felipe; Garcia-Gaitan, Federico; Strachan, David J.; Plechac, Petr; Clark, Stephen R.; Nikolic, Branislav K.

Published

2024

Language

EN