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.
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- 1 Ruprecht-Karls-Universität Heidelberg / Heidelberg University
- 2 Institut für Quantenoptik und Quanteninformation / Institute for Quantum Optics and Quantum Information Innsbruck [IQOQI Innsbruck]
- 3 Institut für Theoretische Physik / Institute for Theoretical Physics, University of Innsbruck [ITP]