SAMOP 2023 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 26: Quantum Gases: Bosons III

Q 26.7: Talk

Wednesday, March 8, 2023, 12:30–12:45, E214

Real-Time Instantons and Self-Similar Scaling in a 1D Spin-1 Bose Gas Far from Equilibrium — •Ido Siovitz, Stefan Lannig, Yannick Deller, Helmut Storbel, Markus Oberthaler, and Thomas Gasenzer — Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg

A system driven far from equilibrium via a parameter quench can show universal dynamics, characterized by self-similar spatio-temporal scaling, associated with the approach to a non-thermal fixed point. The study of such universality classes may assist in a thorough investigation of many systems ranging from the post-inflationary evolution of the universe to low-energy dynamics in cold gases.

Topological excitations in the system are considered to be one of the driving mechanisms of coarsening dynamics in the system and are, as such, a point of interest in the study of far from equilibrium physics. We will discuss the infrared scaling phenomena of a one-dimensional spin-1 Bose gas quenched from the polar phase to the easy-plane phase and provide evidence of the existence of real-time instantons, appearing as vortices in space and time. The latter's contribution to the coarsening dynamics of the system will be shown, and an effective theory describing the mechanism of their appearance will be presented.