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The description of the dynamics of correlated electrons in quantum impurity models is typically described within the nonequilibrium Green function formalism combined with a suitable approximation. One common approach is based on the…

Strongly Correlated Electrons · Physics 2013-06-26 Tal J. Levy , Eran Rabani

We propose to calculate spectral functions of quantum impurity models using the Time Evolving Block Decimation (TEBD) for Matrix Product States. The resolution of the spectral function is improved by a so-called linear prediction approach.…

Strongly Correlated Electrons · Physics 2015-10-28 Martin Ganahl , Markus Aichhorn , Patrik Thunström , Karsten Held , Hans Gerd Evertz , Frank Verstraete

We review two analytical approaches in Dynamical Mean-Field Theory (DMFT) based on a perturbation theory expansion over the electron hopping to and from the self consistent environment. In the first approach the effective single impurity…

Strongly Correlated Electrons · Physics 2007-05-23 I. V. Stasyuk , A. M. Shvaika

We present a minimally entangled typical thermal state (METTS) quantum impurity solver for general multi-orbital systems at finite temperatures. We introduce an improved estimator for the single-particle Green's function that strongly…

Strongly Correlated Electrons · Physics 2024-08-26 Xiaodong Cao , E. Miles Stoudenmire , Olivier Parcollet

We present a numerically stable Quantum Monte Carlo algorithm to calculate zero-temperature imaginary-time Green functions $ G(\vec{r}, \tau) $ for Hubbard type models. We illustrate the efficiency of the algorithm by calculating the…

Condensed Matter · Physics 2009-10-28 F. F. Assaad , M. Imada

Integer programming (IP) is an NP-hard combinatorial optimization problem that is widely used to represent a diverse set of real-world problems spanning multiple fields, such as finance, engineering, logistics, and operations research. It…

Quantum Physics · Physics 2025-08-20 Kapil Goswami , Peter Schmelcher , Rick Mukherjee

The self-consistent theory of the correlation effects in Highly Correlated Systems(HCS) is presented. The novel Irreducible Green's Functions(IGF) method is discused in detail for the Hubbard model and random Hubbard model. The…

Strongly Correlated Electrons · Physics 2008-02-03 A. L. Kuzemsky

A model is proposed to study the hybrid exciton in a quantum dot-dendrimer systems. The semiconductor organic hybrid exciton is studied using a "real space" Green's function method and a diagrammatic technique. The energy of the hybrid…

Mesoscale and Nanoscale Physics · Physics 2016-08-31 Nguyen Que Huong , Joseph L. Birman

We develop a density-matrix renormalization group (DMRG) algorithm for the simulation of quantum circuits. This algorithm can be seen as the extension of time-dependent DMRG from the usual situation of hermitian Hamiltonian matrices to…

We recently proposed a method coupling quantum mechanics (QM) methods and molecular density functional theory (MDFT) to describe mixed quantum-classical systems [J. Chem. Phys. 161, 014113 (2024)]. This approach is particularly appropriate…

Chemical Physics · Physics 2025-11-21 Maxime Labat , Guillaume Jeanmairet , Emmanuel Giner

Quantum algorithms for simulating large and complex molecular systems are still in their infancy, and surpassing state-of-the-art classical techniques remains an ever-receding goal post. A promising avenue of inquiry in the meanwhile is to…

Quantum Physics · Physics 2025-08-07 Soohaeng Yoo Willow , D. ChangMo Yang , Chang Woo Myung

Advancements in the implementation of quantum hardware have enabled the acquisition of data that are intractable for emulation with classical computers. The integration of classical machine learning (ML) algorithms with these data holds…

Quantum Physics · Physics 2025-01-22 Gyungmin Cho , Dohun Kim

An emergent and promising tensor-network-based impurity solver is to represent the path integral as a matrix product state, where the bath is analytically integrated out using Feynman-Vernon influence functional. Here we present an approach…

Strongly Correlated Electrons · Physics 2024-04-04 Ruofan Chen , Xiansong Xu , Chu Guo

In this paper, we present a new version of the $i$QIST software package, which is capable of solving various quantum impurity models by using the hybridization expansion (or strong coupling expansion) continuous-time quantum Monte Carlo…

Computational Physics · Physics 2017-11-22 Li Huang

Using an imaginary-time matrix-product state (MPS) based quantum impurity solver we perform a realistic dynamical mean-field theory (DMFT) calculation combined with density functional theory (DFT) for Sr$_2$RuO$_4$. We take the full…

Strongly Correlated Electrons · Physics 2020-01-22 Nils-Oliver Linden , Manuel Zingl , Claudius Hubig , Olivier Parcollet , Ulrich Schollwöck

Imaginary time evolution is a powerful tool applied in quantum physics, while existing classical algorithms for simulating imaginary time evolution suffer high computational complexity as the quantum systems become larger and more complex.…

Quantum Physics · Physics 2022-10-12 Hao-Nan Xie , Shi-Jie Wei , Fan Yang , Zheng-An Wang , Chi-Tong Chen , Heng Fan , Gui-Lu Long

The non-equilibrium Green's function method combined with density functional theory (NEGF-DFT) provides a rigorous framework for simulating nanoscale electronic transport, but its computational cost scales steeply with system size. Recent…

Mesoscale and Nanoscale Physics · Physics 2025-10-21 Zili Tang , Xiaoxin Xie , Guanwen Yao , Ligong Zhang , Xiaoyan Liu , Xing Zhang , Liu Fei

We present an efficient impurity solver for the dynamical mean-field theory (DMFT). It is based on the separation of bath degrees of freedom into the low energy and the high energy parts. The former is solved exactly using exact…

Strongly Correlated Electrons · Physics 2017-01-02 Hengyue Li , Ning-Hua Tong

We present an efficient algorithm for twirling a multi-qudit quantum state. The algorithm can be used for approximating the twirling operation in an ensemble of physical systems in which the systems cannot be individually accessed. It can…

Quantum Physics · Physics 2007-05-23 Geza Toth , Juan Jose Garcia-Ripoll

We introduce an efficient method to simulate dynamics of an interacting quantum impurity coupled to non-interacting fermionic reservoirs. Viewing the impurity as an open quantum system, we describe the reservoirs by their Feynman-Vernon…

Strongly Correlated Electrons · Physics 2023-06-07 Julian Thoenniss , Michael Sonner , Alessio Lerose , Dmitry A. Abanin