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We present near-term quantum algorithms for auxiliary-field quantum Monte Carlo (AFQMC), viewed as imaginary-time projection for ground-state calculation as an ensemble of one-body propagators driven by stochastic fields $\Omega$. Starting…

Quantum Physics · Physics 2026-03-31 Xiantao Li

We present a continuous-time Monte Carlo method for quantum impurity models, which combines a weak-coupling expansion with an auxiliary-field decomposition. The method is considerably more efficient than Hirsch-Fye and free of time…

Strongly Correlated Electrons · Physics 2008-06-02 Emanuel Gull , Philipp Werner , Olivier Parcollet , Matthias Troyer

We compare the efficiency of different matrix product state (MPS) based methods for the calculation of two-time correlation functions in open quantum systems. The methods are the purification approach [1] and two approaches [2,3] based on…

Strongly Correlated Electrons · Physics 2020-09-17 Stefan Wolff , Ameneh Sheikhan , Corinna Kollath

We use the Shadow Wave Function formalism as a convenient model to study the fermion sign problem affecting all projector Quantum Monte Carlo methods in continuum space. We demonstrate that the efficiency of imaginary time projection…

Computational Physics · Physics 2016-05-04 Francesco Calcavecchia , Markus Holzmann

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

Green's function methods lead to ab initio, systematically improvable simulations of molecules and materials while providing access to multiple experimentally observable properties such as the density of states and the spectral function.…

Quantum Physics · Physics 2023-09-19 Diksha Dhawan , Dominika Zgid , Mario Motta

Auxiliary field quantum Monte Carlo methods for Hubbard models are generally based on a Hubbard-Stratonovitch transformation where the field couples to the z-component of the spin. This transformation breaks SU(2) spin invariance. The…

Strongly Correlated Electrons · Physics 2007-05-23 F. F. Assaad

The recently-introduced self-learning Monte Carlo method is a general-purpose numerical method that speeds up Monte Carlo simulations by training an effective model to propose uncorrelated configurations in the Markov chain. We implement…

Strongly Correlated Electrons · Physics 2017-10-11 Yuki Nagai , Huitao Shen , Yang Qi , Junwei Liu , Liang Fu

A diffusion Monte Carlo algorithm is introduced that can determine the correct nodal structure of the wave function of a few-fermion system and its ground-state energy without an uncontrolled bias. This is achieved by confining signed…

Computational Physics · Physics 2020-02-05 Alexander A. Kunitsa , So Hirata

We show how the worldline quantum Monte Carlo procedure, which usually relies on an artificial time discretization, can be formulated directly in continuous time, rendering the scheme exact. For an arbitrary system with discrete Hilbert…

Condensed Matter · Physics 2009-10-30 N. V. Prokof'ev , B. V. Svistunov , I. S. Tupitsyn

The Hybrid Monte Carlo algorithm for the simulation of QCD with dynamical staggered fermions is compared with Kramers equation algorithm. We find substantially different autocorrelation times for local and nonlocal observables. The…

High Energy Physics - Lattice · Physics 2009-10-28 M. E. Berbenni-Bitsch , A. P. Gottlob , S. Meyer , M. Puetz

In this paper, we present a very fast Monte Carlo scheme for additive processes: the computational time is of the same order of magnitude of standard algorithms for Brownian motions. We analyze in detail numerical error sources and propose…

Computational Finance · Quantitative Finance 2023-07-17 Michele Azzone , Roberto Baviera

Quantum Monte Carlo and semiclassical methods are used to solve two and four site cluster dynamical mean field approximations to the square lattice Hubbard model at half filling and strong coupling. The energy, spin correlation function,…

Strongly Correlated Electrons · Physics 2009-11-11 Andreas Fuhrmann , Satoshi Okamoto , Hartmut Monien , Andrew J. Millis

We present a hybrid Path Integral Monte Carlo (hPIMC) algorithm to calculate real-time quantum thermal correlation functions and demonstrate its application to open quantum systems. The hPIMC algorithm leverages the successes of classical…

Quantum Physics · Physics 2025-06-12 Elliot C. Eklund , Nandini Ananth

We describe the implementation of the frozen-orbital and downfolding approximations in the auxiliary-field quantum Monte Carlo (AFQMC) method. These approaches can provide significant computational savings compared to fully correlating all…

Computational Physics · Physics 2013-11-18 Wirawan Purwanto , Shiwei Zhang , Henry Krakauer

We present an algorithm for measurement of the Green's function in the hybridization expansion continuous-time quantum Monte-Carlo based on continuous estimators. Compared to the standard method, the present algorithm has similar or better…

Strongly Correlated Electrons · Physics 2013-06-17 Pavel Augustinský , Jan Kuneš

We calculate the magnetic moments of light nuclei ($A < 20$) using the auxiliary field diffusion Monte Carlo method and local two- and three-nucleon forces with electromagnetic currents from chiral effective field theory. For all nuclei…

Nuclear Theory · Physics 2023-09-27 J. D. Martin , S. J. Novario , D. Lonardoni , J. Carlson , S. Gandolfi , I. Tews

A ``forward walking'' Quantum Monte Carlo (QMC) algorithm has been developed to calculate correlation functions for the Hamiltonian lattice formulation of U(1) Yang-Mills theory in (2+1) dimensions. It is shown that Wilson loops can be…

High Energy Physics - Lattice · Physics 2009-10-31 Chris J. Hamer , Robert J. Bursill , Maria Samaras

This article describes Monte-Carlo algorithms for charged systems using constrained updates for the electric field. The method is generalized to treat inhomogeneous dielectric media, electrolytes via the Poisson-Boltzmann equation and…

Statistical Mechanics · Physics 2009-11-10 A. C. Maggs

We used methods of Bayesian statistical inference and the principle of maximum entropy to analytically continue imaginary-time Green's function generated in quantum Monte Carlo simulations to obtain the real-time Green's functions. For test…

Condensed Matter · Physics 2009-10-28 J. Bonca , J. E. Gubernatis