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Analytic continuation is a critical step in quantum many-body computations, connecting imaginary-time or Matsubara Green's functions with real-frequency spectral functions, which can be directly compared to experimental results. However,…

Strongly Correlated Electrons · Physics 2025-03-21 Li Huang , Changming Yue

By exploiting the analyticity and boundary value properties of the thermal Green functions that result from the KMS condition in both time and energy complex variables, we treat the general (non-perturbative) problem of recovering the…

Strongly Correlated Electrons · Physics 2007-05-23 G. Cuniberti , E. De Micheli , G. A. Viano

We generalize the recently developed inchworm quantum Monte Carlo method to the full Keldysh contour with forward, backward, and equilibrium branches to describe the dynamics of strongly correlated impurity problems with time dependent…

Strongly Correlated Electrons · Physics 2017-03-07 Andrey E. Antipov , Qiaoyuan Dong , Joseph Kleinhenz , Guy Cohen , Emanuel Gull

We investigate the possibility to assist the numerically ill-posed calculation of spectral properties of interacting quantum systems in thermal equilibrium by extending the imaginary-time simulation to a finite Schwinger-Keldysh contour.…

Strongly Correlated Electrons · Physics 2013-02-25 Andreas Dirks , Martin Eckstein , Thomas Pruschke , Philipp Werner

Finite-temperature quantum field theories are formulated in terms of Green's functions and self-energies on the Matsubara axis. In multi-orbital systems, these quantities are related to positive semidefinite matrix-valued functions of the…

Strongly Correlated Electrons · Physics 2021-10-13 Jiani Fei , Chia-Nan Yeh , Dominika Zgid , Emanuel Gull

A novel scheme to solve the quantum eigenvalue problem through the imaginary-time Green function Monte Carlo method is presented. This method is applicable to the excited states as well as to the ground state of a generic system. We…

Nuclear Theory · Physics 2008-11-26 Taksu Cheon

Path integral Monte Carlo with Green's function analysis allows the sampling of quantum mechanical properties of molecules at finite temperature. While a high-precision computation of the energy of the Born-Oppenheimer surface from path…

Quantum Physics · Physics 2007-05-23 Daejin Shin , Ming-Chak Ho , J. Shumway

A method for analytic continuation of imaginary-time correlation functions (here obtained in quantum Monte Carlo simulations) to real-frequency spectral functions is proposed. Stochastically sampling a spectrum parametrized by a large…

Strongly Correlated Electrons · Physics 2017-06-30 Anders W. Sandvik

We extend finite-temperature tensor network methods to compute Matsubara imaginary-time correlation functions, building on the minimally entangled typical thermal states (METTS) and purification algorithms. While imaginary-time correlation…

Strongly Correlated Electrons · Physics 2022-05-18 Daniel Bauernfeind , Xiaodong Cao , E. Miles Stoudenmire , Olivier Parcollet

We introduce a representation of electron operators as a product of a spin-carry ing fermion and of a phase variable dual to the total charge (slave quantum rotor). Based on this representation, a new method is proposed for solving…

Strongly Correlated Electrons · Physics 2009-11-07 Serge Florens , Antoine Georges

Reliably reconstructing physical fields from sparse sensor data is a challenge that frequently arises in many scientific domains. In practice, the process generating the data often is not understood to sufficient accuracy. Therefore, there…

Machine Learning · Computer Science 2024-01-23 Xihaier Luo , Wei Xu , Yihui Ren , Shinjae Yoo , Balu Nadiga

We propose efficient measurement procedures for the self-energy and vertex function of the Anderson impurity model within the hybridization expansion continuous-time quantum Monte Carlo algorithm. The method is based on the measurement of…

Strongly Correlated Electrons · Physics 2012-06-01 Hartmut Hafermann , Kelly R. Patton , Philipp Werner

We extend the recently developed real-time Diagrammatic Monte Carlo method, in its hybridization expansion formulation, to the full Kadanoff-Baym-Keldysh contour. This allows us to study real-time dynamics in correlated impurity models…

Strongly Correlated Electrons · Physics 2015-05-14 Marco Schiró

We present a minimal pole method for analytically continuing matrix-valued imaginary frequency correlation functions to the real axis, enabling precise access to off-diagonal elements and thus improving the interpretation of self-energies…

Strongly Correlated Electrons · Physics 2024-12-16 Lei Zhang , Yang Yu , Emanuel Gull

We present an analytical and numerical study of the two-dimensional capillary-driven thin film equation. In particular, we focus on the intermediate asymptotics of its solutions. Linearising the equation enables us to derive the associated…

Analysis of PDEs · Mathematics 2014-11-11 Michael Benzaquen , Thomas Salez , Élie Raphaël

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

A Monte Carlo sampling of diagrammatic corrections to the non-crossing approximation is shown to provide numerically exact estimates of the long-time dynamics and steady state properties of nonequilibrium quantum impurity models. This…

Strongly Correlated Electrons · Physics 2012-12-21 Emanuel Gull , David R. Reichman , Andrew J. Millis

An acceleration of continuous time quantum Monte Carlo (CTQMC) methods is a potentially interesting branch of work as they are matchless as impurity solvers of a density functional theory in combination with a dynamical mean field theory…

Strongly Correlated Electrons · Physics 2019-08-07 Taegeun Song , Hunpyo Lee

We present a new method for extracting numerically exact imaginary-time Green functions from standard Hirsch-Fye quantum Monte Carlo (HF-QMC) simulations within dynamical mean-field theory. By analytic continuation, angular resolved spectra…

Strongly Correlated Electrons · Physics 2007-12-11 N. Blümer

The impurity Green's function Gf in the local non-Fermi liquid state is evaluated by means of the continuous-time quantum Monte Carlo method extended to the multichannel Anderson model. For N=M (where N and M are numbers of spin components…

Strongly Correlated Electrons · Physics 2015-05-20 Junya Otsuki