Special Physics Colloquium: Equilibration towards positive and negative absolute temperatures
Prof. Achim Rosch, Cologne University
Progress in ultrafast experiments in solids and, especially, in ultracold atom systems allows for new studies investigating how interacting many-particle quantum system reach their thermal equilibrium state.
Starting from bosonic and fermionic Hubbard models, we investigate theoretically how and how fast thermal equilibrium states can be reached after a sudden perturbation of the system.
In cases where the Hamiltonian is bounded from above, it is, for example, possible to realize states where the absolute temperature is negative so that high-energy states are more probable than low-energy states. We also discuss how the building up of thermal fluctuations and associated hydrodynamic long-time tails are the ultimate bottleneck for equilibration: thermal equilibrium is only approached very slowly.
Event Organiser: Dr. Eran Sela