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A powerful way to guarantee the absence of a sign problem in determinantal quantum Monte Carlo simulations is imposing a particular type of anti-unitary symmetries. It is shown that these same symmetries give rise to constraints on…

Strongly Correlated Electrons · Physics 2025-09-08 Xu Zhang , Nick Bultinck

The mystery of the infamous sign problem in quantum Monte Carlo simulations mightily restricts applications of the method in fermionic and frustrated systems. A recent work [Science 375, 418 (2022)] made a remarkable breakthrough in the…

Statistical Mechanics · Physics 2024-09-27 Nvsen Ma , Jun-Song Sun , Gaopei Pan , Chen Cheng , Zheng Yan

The shell model Monte Carlo (SMMC) method is a powerful method for calculating exactly (up to statistical errors) thermal observables and statistical properties of atomic nuclei. However, its application has been limited by a sign problem…

Nuclear Theory · Physics 2025-01-08 Y. Alhassid , P. Fanto , C. Özen

In this paper, we present a quasi-polynomial time classical algorithm that estimates the partition function of quantum many-body systems at temperatures above the thermal phase transition point. It is known that in the worst case, the same…

Quantum Physics · Physics 2021-02-22 Aram Harrow , Saeed Mehraban , Mehdi Soleimanifar

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…

When one tries to simulate quantum spin systems by the Monte Carlo method, often the 'minus-sign problem' is encountered. In such a case, an application of probabilistic methods is not possible. In this paper the method has been proposed…

Statistical Mechanics · Physics 2009-11-11 Jacek Wojtkiewicz

Mean-field molecular dynamics based on path integrals is used to approximate canonical quantum observables for particle systems consisting of nuclei and electrons. A computational bottleneck is the sampling from the Gibbs density of the…

Numerical Analysis · Mathematics 2023-11-30 Xin Huang , Petr Plechac , Mattias Sandberg , Anders Szepessy

A fundamental open issue in physics is whether and how the fermion sign problem in quantum Monte Carlo (QMC) simulations can be solved generically. Here, we show that Majorana-time-reversal (MTR) symmetries can provide a unifying principle…

Strongly Correlated Electrons · Physics 2016-12-26 Zi-Xiang Li , Yi-Fan Jiang , Hong Yao

We present extensive new \emph{ab initio} path integral Monte Carlo (PIMC) results for a variety of structural properties of warm dense hydrogen and beryllium. To deal with the fermion sign problem -- an exponential computational bottleneck…

For some models of interacting fermions the known solution to the notorious sign-problem in Monte Carlo (MC) simulations is to work with macroscopic fermionic determinants; the price, however, is a macroscopic scaling of the numerical…

Strongly Correlated Electrons · Physics 2009-11-10 Evgueni Bourovski , Nikolay Prokof'ev , Boris Svistunov

Strongly-coupled fermionic systems can support a variety of low-energy phenomena, giving rise to collective condensation, symmetry breaking and a rich phase structure. We explore the potential of worldline Monte Carlo methods for analyzing…

High Energy Physics - Theory · Physics 2010-11-11 Gerald Dunne , Holger Gies , Klaus Klingmuller , Kurt Langfeld

QCD at fixed baryon number can be formulated in terms of transfer matrices explicitly defined in the canonical sectors. In the heavy-dense limit, the fermionic contributions to the canonical partition functions in terms of Polyakov loops…

High Energy Physics - Lattice · Physics 2021-10-29 Patrick Bühlmann , Urs Wenger

If the fermion mass is large enough, the phase of the fermion determinant of QCD at finite density is strongly correlated with the imaginary part of the Polyakov loop. This fact can be exploited to reduce the fluctuations of the phase…

High Energy Physics - Lattice · Physics 2015-06-25 Philippe de Forcrand , Victor Laliena

A digital computer is generally believed to be an efficient universal computing device; that is, it is believed able to simulate any physical computing device with an increase in computation time of at most a polynomial factor. This may not…

Quantum Physics · Physics 2017-02-20 Peter W. Shor

The great majority of algorithms employed in the study of lattice field theory are based on Monte Carlo's importance sampling method, i.e. on probability interpretation of the Boltzmann weight. Unfortunately in many theories of interest one…

High Energy Physics - Lattice · Physics 2016-06-03 Lorenzo Bongiovanni

The Fermi polaron problem, which describes a mobile impurity that interacts with a spin-polarized Fermi sea, is a paradigmatic system in quantum many-body physics and has been challenging to address quantitatively in its strong coupling…

Quantum Gases · Physics 2025-11-26 S. Ramachandran , S. Jensen , Y. Alhassid

We present a real-time quantum Monte Carlo algorithm that simulates the dynamics of open quantum systems by stochastically compressing and evolving the density matrix under both Markovian and non-Markovian master equations. Our algorithm…

Quantum Physics · Physics 2025-09-11 Tong Shen , Daniel A. Lidar

The sign cancellation between scattering amplitudes makes fermions different from bosons. We systematically investigate Feynman diagrams' fermionic sign structure in a representative many-fermion system---a uniform Fermi gas with Yukawa…

Quantum Gases · Physics 2021-03-31 Bao-Zong Wang , Peng-Cheng Hou , Youjin Deng , Kristjan Haule , Kun Chen

We calculate the finite-temperature density and polarization equations of state of one-dimensional fermions with a zero-range interaction, considering both attractive and repulsive regimes. In the path-integral formulation of the…

Quantum Gases · Physics 2018-09-19 Andrew C. Loheac , Jens Braun , Joaquín E. Drut

A Path Integral Monte Carlo method is used to investigate the thermodynamics of nuclear like systems. Systems composed of bosons or fermions interracting via a Lennard-Jones potential with periodic boundary conditions were simulated and the…

Nuclear Theory · Physics 2010-09-02 A. H. Raduta