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DY: Fachverband Dynamik und Statistische Physik

DY 23: Stochastic Thermodynamics

DY 23.13: Talk

Wednesday, March 20, 2024, 12:45–13:00, BH-N 128

Geometrically frustrated systems which are as singles hotter than in company — •Wolfgang Bauer — Dept. of Internal Medicine I, UKW, Würzburg, Germany

Systems of same temperature, which are brought from initial isolation to weak thermal coupling, maintain their temperature, which is equivalent to that of the combined system. Any other scenario would be in conflict with our notion of thermal stability and the 2nd law of thermodynamics. Special geometrically frustrated systems (GFSs), which are constraint to reside at negative Boltzmann temperature, challenge the above notion. When brought in weak thermal contact, the assembly of GFSs is in equilibrium cooler than its constituents, and may even exhibit positive Boltzmann temperatures. The 2nd law of thermodynamics would imply heat flow related to the gradient of Boltzmann temperatures between a single GFS and the residual assembly under equilibrium conditions. This conflict is resolved by considering the canonical temperature of a GFS, derived from information theory, which differs from its Boltzmann temperature. We show, that the gradient of Boltzmann temperatures predicts the stochastic drift of the most probable state of a GFS within its environment, whereas the canonical temperature gradient defines the direction of heat flow, which restores the 2nd law of thermodynamics.

Keywords: thermodynamics; negative temperature; stochastic thermodynamics; second law of thermodynamics; entropy