Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 44: Nonequilibrium Quantum Systems I (joint session TT/DY)
TT 44.3: Talk
Wednesday, March 11, 2026, 10:00–10:15, CHE/0091
Hybrid quantum--classical matrix-product state and Lanczos methods for electron--phonon systems with strong electronic correlations: Application to disordered systems coupled to Einstein phonons — •Heiko Georg Menzler1, Suman Mondal2, and Fabian Heidrich-Meisner1 — 1Institut für Theoretische Physik, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany — 2Max Planck Institute for the Physics of Complex Systems, Dresden
We present two quantum-classical hybrid methods for simulating the time-dependence of electron-phonon systems that treat electronic correlations numerically exactly and optical-phonon degrees of freedom classically. These are a time-dependent Lanczos and a matrix-product state method, each combined with the multi-trajectory Ehrenfest approach. Due to the approximations, reliable results are expected for the adiabatic regime of small phonon frequencies. We discuss the convergence properties of both methods for a system of interacting spinless fermions in one dimension and provide a benchmark for the Holstein chain. As a first application, we study the decay of charge density wave order in a system of interacting spinless fermions coupled to Einstein oscillators and in the presence of quenched disorder. We investigate the dependence of the relaxation dynamics on the electron-phonon coupling strength and provide numerical evidence that the coupling of strongly disordered systems to classical oscillators leads to delocalization, thus destabilizing the (finite-size) many-body localization in this system.
This research is supported by the DFG (Deutsche Forschungsgemeinschaft) via SFB 1073 and FOR 5522.
Keywords: Phonons; Disorder; Matrix-Product States; Multi-trajectory Ehrenfest