Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 22: Many-body Systems: Equilibration, Chaos, and Localization (joint session DY/TT)

TT 22.4: Talk

Tuesday, March 18, 2025, 14:45–15:00, H37

Effects of chaos in Bose-Hubbard systems with few degrees of freedom. The smallest possible heat engine? — •Viviane Bauer, Nico Fink, and James Anglin — Physics Department and Research Center OSCAR, RPTU Kaiserslautern-Landau

Microscopic engines are a research focus in both biochemistry and nanotechnology. While other forms of engines besides heat engines are also being considered, the fully microscopic limit of a heat engine is a fundamentally important problem in physics. What happens to thermodynamics when not only the working fluid and mechanism of a heat engine, but even the hot and cold reservoirs are microscopic?

To realize such microscopic heat baths, we turn to the process of chaotic ergodization, studied in Bose-Hubbard dimers and trimers.

One realization we currently study is based on two Bose-Hubbard trimers, which allow energy and particle transport between them. The particle transport is furthermore coupled to a mass, so our engine works against a force to lift it. Moreover, we have identified a dynamic mechanism which can stabilize this lifting process. The result is a system which operates just like a heat engine, except for being fully microscopic. The structure of coupled chaotic subsystems both supports and requires an understanding of the fully microscopic heat engine in terms of open-system control.

Keywords: nonlinear dynamics; chaotic ergodization; thermalisation; microscopic engine