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We introduce a semistochastic implementation of the power method to compute, for very large matrices, the dominant eigenvalue and expectation values involving the corresponding eigenvector. The method is semistochastic in that the matrix…

Strongly Correlated Electrons · Physics 2013-10-24 F. R. Petruzielo , A. A. Holmes , Hitesh J. Changlani , M. P. Nightingale , C. J. Umrigar

We present a set of related Hybrid Monte Carlo methods to simulate an arbitrary number of dynamical overlap fermions. Each fermion is represented by a chiral pseudo-fermion field. The new algorithm reduces critical slowing down in the…

High Energy Physics - Lattice · Physics 2009-11-11 Thomas DeGrand , Stefan Schaefer

Quantum Monte Carlo methods are sophisticated numerical techniques for simulating interacting quantum systems. In some cases, however, they suffer from the notorious "sign problem" and become too inefficient to be useful. A recent…

Strongly Correlated Electrons · Physics 2008-05-16 K. S. D. Beach , Matthieu Mambrini , Fabien Alet

The fermion sign problem constitutes a fundamental computational bottleneck across a plethora of research fields in physics, quantum chemistry and related disciplines. Recently, it has been suggested to alleviate the sign problem in…

Quantum Monte Carlo (QMC) simulations constitute nowadays one of the most powerful methods to study strongly correlated quantum systems, provided that no "sign problem" arises. However, many systems of interest, including highly frustrated…

Strongly Correlated Electrons · Physics 2022-03-30 Andreas Honecker , Lukas Weber , Philippe Corboz , Frédéric Mila , Stefan Wessel

We propose a new method for simulating QCD at finite density, where interesting phases such as the color superconductivity phase is conjectured to appear. The method is based on a general factorization property of distribution functions of…

High Energy Physics - Lattice · Physics 2017-08-23 Jun Nishimura

We present results of the numerical simulation of the two-dimensional Thirring model at finite density and temperature. The severe sign problem is dealt with by deforming the domain of integration into complex field space. This is the first…

High Energy Physics - Lattice · Physics 2017-01-11 Andrei Alexandru , Gokce Basar , Paulo F. Bedaque , Gregory W. Ridgway , Neill C. Warrington

We train a pair of autoregressive models to construct zero-mean control variates to mitigate the sign problem in quantum Monte Carlo simulations. The two autoregressive networks are confined to the positive- and negative-sign sectors with…

Strongly Correlated Electrons · Physics 2026-05-27 Bei Qiao , Lei Wang

We derive an exact representation of the massless Schwinger model on the lattice in terms of dual variables which are configurations of loops, dimers and plaquette occupation numbers. When expressed with the dual variables the partition sum…

High Energy Physics - Lattice · Physics 2015-12-09 Christof Gattringer , Thomas Kloiber , Vasily Sazonov

We investigate the simulation of fermionic systems on a quantum computer. We show in detail how quantum computers avoid the dynamical sign problem present in classical simulations of these systems, therefore reducing a problem believed to…

Condensed Matter · Physics 2009-02-05 G. Ortiz , J. E. Gubernatis , E. Knill , R. Laflamme

In this paper, we discuss various problems in the usage and definition of risk matrices. We give an overview of the general process of risk assessment with risk matrices and ordinal scales. Furthermore, we explain the fallacies in each…

Risk Management · Quantitative Finance 2021-03-10 Michael Krisper

Quantum Monte Carlo belongs to the most accurate simulation techniques for quantum many-particle systems. However, for fermions, these simulations are hampered by the sign problem that prohibits simulations in the regime of strong…

Computational Physics · Physics 2020-10-28 A. Yilmaz , K. Hunger , T. Dornheim , S. Groth , M. Bonitz

Being motivated by the surge of fermionic quantum Monte Carlo simulations at finite temperature, we present a detailed analysis of the permutation-cycle properties of path integral Monte Carlo (PIMC) simulations of degenerate electrons.…

Computational Physics · Physics 2019-07-24 Tobias Dornheim , Simon Groth , Alexei Filinov , Michael Bonitz

We consider a hybrid Monte Carlo algorithm which is applicable to lattice theories defined on Lefschetz thimbles. In the algorithm, any point (field configuration) on a thimble is parametrized uniquely by the flow-direction and the…

High Energy Physics - Lattice · Physics 2015-06-17 H. Fujii , D. Honda , M. Kato , Y. Kikukawa , S. Komatsu , T. Sano

We have developed a method to derive the (approximate) quark contribution to the fermion free energy of QCD on a lattice, at finite temperature and chemical potential, with Kogut-Susskind fermions in the flavor basis. We show here the…

High Energy Physics - Lattice · Physics 2011-01-10 Sergio Caracciolo , Fabrizio Palumbo

Monte Carlo simulations are based on the manipulation of random numbers to evaluate probable outcomes, with applicability in a variety of different fields. By assigning probabilities, which can be determined a priori, to various events, it…

Physics Education · Physics 2022-01-03 Parasuraman Swaminathan

Simulation offers a simple and flexible way to estimate the power of a clinical trial when analytic formulae are not available. The computational burden of using simulation has, however, restricted its application to only the simplest of…

We study the 2+1 dimensional XY model at nonzero chemical potential $\mu$ on deformed integration manifolds, with the aim of alleviating its sign problem. We investigate several proposals for the deformations, and considerably improve on…

High Energy Physics - Lattice · Physics 2022-10-12 Matteo Giordano , Kornel Kapas , Sandor D Katz , Attila Pasztor , Zoltan Tulipant

We study the expectation value of the phase of the fermion determinant for Wilson lattice fermions with chemical potential. We use quenched SU(3) ensembles and implement a recently proposed exact dimensional reduction of the fermion…

High Energy Physics - Lattice · Physics 2009-11-23 Julia Danzer , Christof Gattringer , Ludovit Liptak , Marina Marinkovic

We describe an embarrassingly parallel, anytime Monte Carlo method for likelihood-free models. The algorithm starts with the view that the stochasticity of the pseudo-samples generated by the simulator can be controlled externally by a…

Machine Learning · Computer Science 2015-12-03 Edward Meeds , Max Welling