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THU: Thursday Contributed Sessions

THU 12: Quantum Thermalization: Contributed Session to Symposium

THU 12.7: Talk

Thursday, September 11, 2025, 15:45–16:00, ZHG105

Hierarchy of the relaxation timescales in a disordered spin-1/2 XX ladder — •Kadir Çeven, Lukas Peinemann, and Fabian Heidrich-Meisner — Institut für Theoretische Physik, Georg- August-Universität Göttingen, Göttingen, Germany

Understanding the timescales associated with relaxation to equilibrium in closed quantum many-body systems is one of the central focuses in the study of their non-equilibrium dynamics. At late times, these relaxation processes are believed to exhibit universal behavior, emerging from the inherent randomness of chaotic Hamiltonians. In this work, we investigate a disordered spin-1/2 XX ladder—an experimentally realizable model known for its diffusive dynamics—to explore the connection between transport properties and spectral measures derived solely from the system’s energy levels via these relaxation timescales.

We begin by analyzing the spectral form factor, which reveals the timescale at which the system begins to exhibit random matrix theory (RMT) statistics, known as the RMT time. We then determine the Thouless time—the time for particle to diffuse across the entire finite system—through transport analysis of the disordered model. Our numerical results confirm that, during relaxation, the RMT time occurs significantly later than the Thouless time, signalling distinct temporal regimes in the system’s approach to equilibrium.

We acknowledge funding from the Deutsche Forschungsgemeinschaft (German Research Foundation) within the Research Unit FOR5522 (Project No. 499180199).

Keywords: spin ladder; Thouless time; relaxation; thermalization; non-equilibrium quantum physics