Dresden 2026 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 23: Correlated Electrons – Poster I
TT 23.26: Poster
Montag, 9. März 2026, 18:00–20:00, P1
Non-equilibrium DMFT solved with the help of Tensor Cross Interpolation — •Bastian Schindler1, Eva Paprotzki1,2, and Martin Eckstein1,2 — 1I. Institute for Theoretical Physics, University of Hamburg, Notkestraße 9-11, 22607 Hamburg, Germany — 2The Hamburg Centre for Ultrafast Imaging, Hamburg, Germany
The non-perturbative solution of the quantum impurity problem provides the biggest computational challenge when DMFT is applied in non-equilibrium. Most applications of non-equilibrium DMFT are based on simplified perturbative solutions [1]. In diagrammatic approaches to the impurity model, the numerical integration of high-dimensional expressions poses the main computational bottleneck, limiting feasible expansion orders and the number of accessible time steps. Tensor Cross Interpolation (TCI) has recently emerged as a powerful technique to mitigate the exponential scaling of computational cost with dimensionality [2]. In this work, we apply TCI to diagrammatic expressions obtained from a pseudo-particle expansion of the hybridization around the atomic limit in the non-equilibrium steady state. We demonstrate that, with an appropriate parametrization and an FFT-based integration scheme [3], TCI yields a significant speed-up for higher-order contributions. Moreover, we employ TCI to efficiently evaluate the multidimensional integrals required for higher-order spectroscopy, in particular time-resolved resonant inelastic x-ray scattering.
[1] Murakami et al., Rev. Mod. Phys. 97.3 (2025)
[2] Núñez Fernández, et al., SciPost Physics 18.3 (2025)
[3] Eckstein, arXiv:2410.19707 (2024)
Keywords: Non-Equilibirum; Dynamical Mean-Field Theory; Tensor Cross Interpolation; Impurity Solver; Strong-Coupling Expansion