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Quantum annealing is a generic solver of the optimization problem that uses fictitious quantum fluctuation. Its simulation in classical computing is often performed using the quantum Monte Carlo simulation via the Suzuki--Trotter…

Quantum Physics · Physics 2016-12-15 Masayuki Ohzeki

We apply constant imaginary offsets to the path integral for a reduction of the sign problem in the Hubbard model. These simple transformations enhance the quality of results from HMC calculations without compromising the speed of the…

Strongly Correlated Electrons · Physics 2024-07-11 Christoph Gäntgen , Evan Berkowitz , Thomas Luu , Johann Ostmeyer , Marcel Rodekamp

We review the theory and applications of complex stochastic quantization to the quantum many-body problem. Along the way, we present a brief overview of a number of ideas that either ameliorate or in some cases altogether solve the sign…

The quantum chromodynamics (QCD) phase diagram, which reveals the state of strongly interacting matter at different temperatures and densities, is key to answering open questions in physics, ranging from the behavior of particles in neutron…

We introduce a Monte Carlo scheme for sampling bold-line diagrammatic series specifying an unknown function in terms of itself. The range of convergence of this bold(-line) diagrammatic Monte Carlo (BMC) is significantly broader than that…

Statistical Mechanics · Physics 2009-11-13 Nikolay Prokof'ev , Boris Svistunov

This article gives an introduction to the multilevel blocking (MLB) approach to both the fermion and the dynamical sign problem in path-integral Monte Carlo simulations. MLB is able to substantially relieve the sign problem in many…

Statistical Mechanics · Physics 2007-05-23 R. Egger , C. H. Mak

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

Many fascinating systems suffer from a severe (complex action) sign problem preventing us from calculating them with Markov Chain Monte Carlo simulations. One promising method to alleviate the sign problem is the transformation of the…

Strongly Correlated Electrons · Physics 2022-11-18 Marcel Rodekamp , Christoph Gäntgen

State-of-the-art algorithms for simulating fermions coupled to gauge fields often rely on integrating fermion degrees of freedom. While successful in simulating QCD at zero chemical potential, at finite density these approaches are hindered…

High Energy Physics - Lattice · Physics 2024-02-05 Joao C. Pinto Barros , Thea Budde , Marina Krstic Marinkovic

We develop a strong-coupling perturbation scheme for a generic Hubbard model around a half-filled particle-hole-symmetric reference system, which is free from the fermionic sign problem. The approach is based on the lattice determinantal…

Strongly Correlated Electrons · Physics 2026-05-15 Sergei Iskakov , Mikhail I. Katsnelson , Alexander I. Lichtenstein

Many research programs aiming to deal with the sign problem were proposed since the advent of lattice field theory. Several of these try to achieve this by exploiting properties of analytic functions. This is also the case for our study.…

High Energy Physics - Lattice · Physics 2018-11-07 Błażej Ruba , Jacek Wosiek

The sign problem in quantum Monte Carlo calculations is analyzed using the meron-cluster solution. The concept of merons can be used to solve the sign problem for a limited class of models. Here we show that the method can be used to…

Strongly Correlated Electrons · Physics 2009-11-10 Sara Bergkvist , Patrik Henelius , Anders Rosengren

We study the utility of a complex Langevin (CL) equation as an alternative for the Monte Carlo (MC) procedure in the evaluation of expectation values occurring in fermionic many-body problems. We find that a CL approach is natural in cases…

Nuclear Theory · Physics 2009-11-06 Chris Adami , Steven E. Koonin

We study the heavy-dense limit of QCD on the lattice with heavy quarks at high density. The effective three dimensional theory has a sign problem which is alleviated by sign optimization where the path integration domain is deformed in…

High Energy Physics - Theory · Physics 2023-12-14 Gokce Basar , Joseph Marincel

As an intrinsically-unbiased approach, quantum Monte Carlo (QMC) is of vital importance in understanding correlated phases of matter. Unfortunately, it often suffers notorious sign problem when simulating interacting fermion models. Here,…

Strongly Correlated Electrons · Physics 2022-11-03 Zi-Xiang Li , Zhou-Quan Wan , Hong Yao

The nuclear shell model is known to describe the properties of various nuclei extremely well. However, the auxiliary-field quantum Monte Carlo calculations cannot be applied to it with general interactions due to the sign problem. The model…

Nuclear Theory · Physics 2025-08-22 Yuhma Asano , Yuta Ito , Jun Nishimura , Noritaka Shimizu

Quantum Monte Carlo (QMC) is an advanced simulation methodology for studies of manybody quantum systems. In this review, we focus on the electronic structure QMC, i.e., methods relevant for systems described by the electron-ion…

Other Condensed Matter · Physics 2010-08-16 Michal Bajdich , Lubos Mitas

We discuss finite temperature quantum Monte Carlo methods in the framework of the interacting nuclear shell model. The methods are based on a representation of the imaginary-time many-body propagator as a superposition of one-body…

Nuclear Theory · Physics 2009-11-06 Y. Alhassid

We investigate the sign problem for full configuration interaction quantum Monte Carlo (FCIQMC), a stochastic algorithm for finding the ground state solution of the Schr\"odinger equation with substantially reduced computational cost…

Computational Physics · Physics 2014-11-05 James J. Shepherd , Gustavo E. Scuseria , James S. Spencer

We propose a novel approach toward the general solution of the sign problem in real-time path-integral simulations. Using a recursive multilevel blocking strategy, this method circumvents the sign problem by synthesizing the phase…

Chemical Physics · Physics 2009-10-31 C. H. Mak , R. Egger