Condensed Matter Seminar: Fermi Pasta Ulam Tsingou chain: Thermalization and anomalous conduction

Fermi-Pasta-Ulam-Tsingou (FPUT) chain is a simplified model of a one dimensional crystal, consisting of atoms linked by anharmonic chains. This model was introduced in the fifties of the previous century in Los Alamos to study heat conduction in solids. Despite the fact that 70 years have passed, the Fermi–Pasta–Ulam-Tsingou system has not yet been fully understood.

In this talk I will show how the wave turbulence formalism describes how the system reaches thermal equilibrium. I will show that it is an interaction between its six wave numbers that lead to thermalization of the system for weak nonlinearity. 

I will also explain how the phenomenon of its anomalous conduction appears in the FPUT system. It turns out that the anomalous conduction is the result of the presence of long waves that rapidly propagate from one thermostat to the other without interacting with other modes.