Anna Kauch
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Two-site entanglement in the two-dimensional Hubbard model Open
With this data set, we aim to make all data published in [1] Bippus. et. al Two-site entanglement in the two-dimensional Hubbard model (2025) arXiv:2506.09780 publicly available. In this study, the entanglement properties of the 2D Hubbard…
Ladder equation for the three-particle vertex and its approximate solution Open
We generalize the three two-particle Bethe-Salpeter equations to ten three-particle ladders. These equations are exact and yield the exact three-particle vertex, if we knew the three-particle vertex irreducible in one of the ten channels. …
A causality-based divide-and-conquer algorithm for nonequilibrium Green's function calculations with quantics tensor trains Open
We propose a causality-based divide-and-conquer algorithm for nonequilibrium Green's function calculations with quantics tensor trains. This algorithm enables stable and efficient extensions of the simulated time domain by exploiting the c…
Entanglement in the pseudogap regime of cuprate superconductors Open
We find a strongly enhanced entanglement within the pseudogap regime of the Hubbard model. This entanglement is estimated from the quantum Fisher information and, avoiding the ill-conditioned analytical continuation, the quantum variance. …
Entanglement across scales: Quantics tensor trains as a natural framework for renormalization Open
Understanding entanglement remains one of the most intriguing problems in physics. While particle and site entanglement have been studied extensively, the investigation of length or energy scale entanglement, quantifying the information ex…
Diagnosing phase transitions through time scale entanglement Open
Spatial entanglement of wave functions has matured into an enthralling and very active research area. Here, we unearth a completely different kind of entanglement, the entanglement between different time scales. This is feasible through qu…
Analytical expression for $\pi$-ton vertex contributions to the optical conductivity Open
Vertex corrections from the transversal particle-hole channel, so-called \pi -tons, are gene- ric in models for strongly correlated electron systems and can lead to a displaced Drude peak (DDP). Here, we derive the analytical expression fo…
Analytical expression for $\pi$-ton vertex contributions to the optical conductivity Open
Vertex corrections from the transversal particle-hole channel, so-called \pi -tons, are gene- ric in models for strongly correlated electron systems and can lead to a displaced Drude peak (DDP). Here, we derive the analytical expression fo…
Two-particle calculations with quantics tensor trains: Solving the parquet equations Open
We present an application of quantics tensor trains (QTTs) and tensor cross interpolation (TCI) to the solution of a full set of self-consistent equations for multivariate functions, the so-called parquet equations. We show that the steps …
Data for "Two-particle calculations with quantics tensor trains -- solving the parquet equations" Open
This data repository contains the original figures, numerical (raw) data and plot scripts to reproduce the figures from the publication "Two-particle calculations with quantics tensor trains -- solving the parquet equations" at Physical Re…
Ladder equation for the three-particle vertex and its approximate solution Open
We generalize the three two-particle Bethe-Salpeter equations to ten three-particle ladders. These equations are exact and yield the exact three-particle vertex, if we knew the three-particle vertex irreducible in one of the ten channels. …
Two-site reduced density matrix from one- and two-particle Green's functions Open
Strongly correlated electron systems are challenging to calculate, and entanglement in such systems is not widely analyzed. We present an approach that can be used as a post-processing step for calculating the two-site reduced density matr…
A functional-analysis derivation of the parquet equation Open
The parquet equation is an exact field-theoretic equation known since the 60s that underlies numerous approximations to solve strongly correlated Fermion systems. Its derivation previously relied on combinatorial arguments classifying all …
Report on 2305.16050v2 Open
The parquet equation is an exact field-theoretic equation known since the 60s that underlies numerous approximations to solve strongly correlated Fermion systems.Its derivation previously relied on combinatorial arguments classifying all d…
Report on 2305.16050v1 Open
The parquet equation is an exact field-theoretic equation known since the 60s that underlies numerous approximations to solve strongly correlated Fermion systems.Its derivation previously relied on combinatorial arguments classifying all d…
Report on 2305.16050v1 Open
The parquet equation is an exact field-theoretic equation known since the 60s that underlies numerous approximations to solve strongly correlated Fermion systems.Its derivation previously relied on combinatorial arguments classifying all d…
Report on 2305.16050v1 Open
The parquet equation is an exact field-theoretic equation known since the 60s that underlies numerous approximations to solve strongly correlated Fermion systems.Its derivation previously relied on combinatorial arguments classifying all d…
A functional-analysis derivation of the parquet equation Open
The parquet equation is an exact field-theoretic equation known since the 60s that underlies numerous approximations to solve strongly correlated Fermion systems. Its derivation previously relied on combinatorial arguments classifying all …
Multiscale Space-Time Ansatz for Correlation Functions of Quantum Systems Based on Quantics Tensor Trains Open
The correlation functions of quantum systems—central objects in quantum field theories—are defined in high-dimensional space-time domains. Their numerical treatment thus suffers from the curse of dimensionality, which hinders the applicati…
Multiscale space-time ansatz for correlation functions of quantum systems based on quantics tensor trains Open
Correlation functions of quantum systems -- central objects in quantum field theories -- are defined in high-dimensional space-time domains. Their numerical treatment thus suffers from the curse of dimensionality, which hinders the applica…
Photoexcitations in the Hubbard model: Generalized Loschmidt amplitude analysis of impact ionization in small clusters Open
We study photoexcitations in small Hubbard clusters of up to 12 sites, some\nof which show an increase of the double occupation after the electric field\npulse through impact ionization. Here, the time-dependent electromagnetic field\nis i…
The plain and simple parquet approximation: single- and multi-boson\n exchange in the two-dimensional Hubbard model Open
The parquet approach to vertex corrections is unbiased but computationally\ndemanding. Most applications are therefore restricted to small cluster sizes or\nrely on various simplifying approximations. We have recently shown that the\nboson…
Photoexcitations in the Hubbard model -- generalized Loschmidt amplitude analysis of impact ionization in small clusters Open
We study photoexcitations in small Hubbard clusters of up to 12 sites, some of which show an increase of the double occupation after the electric field pulse through impact ionization. Here, the time-dependent electromagnetic field is intr…
Efficient Adaptive Computation of the Dynamics of Mott Transistors Open
We investigate time-adaptive Magnus-type integrators for the numerical approximation of a Mott transistor. The rapidly attenuating electromagnetic field calls for adaptive choice of the time steps. As a basis for step selection, asymptotic…
Broadening and sharpening of the Drude peak through antiferromagnetic fluctuations Open
Antiferromagnetic or charge density wave fluctuations couple with light through the recently discovered π-ton contribution to the optical conductivity, and quite generically constitute the dominant vertex corrections in low-dimensional cor…
Self-consistent ladder dynamical vertex approximation Open
We present and implement a self-consistent D$\\Gamma$A approach for\nmulti-orbital models and ab initio materials calculations. It is applied to the\none-band Hubbard model at various interaction strengths with and without\ndoping, to the …
Enhancement of impact ionization in Hubbard clusters by disorder and next-nearest-neighbor hopping Open
We perform time-resolved exact diagonalization of the Hubbard model with time\ndependent hoppings on small clusters of up to $12$ sites. Here, the time\ndependence originates from a classic electromagnetic pulse, which mimics the\nimpact o…
Solving the Bethe-Salpeter equation with exponential convergence Open
The Bethe-Salpeter equation plays a crucial role in understanding the physics of correlated fermions, relating to optical excitations in solids as well as resonances in high-energy physics. Yet, it is notoriously difficult to control numer…