Equal-time approach to real-time dynamics of quantum fields

Abstract:

We employ the equal-time formulation of quantum field theory to derive effective kinetic theories, first for a weakly coupled non-relativistic Bose gas, and then for a strongly correlated system of self-interacting $N$-component fields. Our results provide the link between state-of-the-art measurements of equal-time effective actions using quantum simulator platforms, as employed in [Phys. Rev. X 10, 011020 (2020); Nat. Phys. 16, 1012 (2020)], and observables underlying effective kinetic or hydrodynamic descriptions. New non-perturbative approximation schemes can be developed and certified this way, where the a priori time-local formulation of the equal-time effective action has crucial advantages over the conventional closed-time-path approach which is non-local in time.

R. Ott, T. V. Zache, J. Berges, „Equal-time approach to real-time dynamics of quantum fields“,
SciPost Phys. 14, 011 (2023).

https://scipost.org/10.21468/SciPostPhys.14.2.011

Related to Project B03, B04, A03, A04, A01