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We develop a highly efficient method to numerically simulate thermal fluctuations and correlations in non-relativistic continuous bosonic one-dimensional systems. We start by noticing the equivalence of their description through the…

Quantum Gases · Physics 2020-04-20 Stefan Beck , Igor E. Mazets , Thomas Schweigler

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

Direct sampling of multi-dimensional systems with quantum Monte Carlo methods allows exact account of many-body effects or particle correlations. The most straightforward approach to solve the Schr\"odinger equation, Diffusion Monte Carlo,…

Quantum Physics · Physics 2017-09-07 Ilkka Ruokosenmäki , Tapio T. Rantala

One of the most important quantities characterizing the microscopic properties of quantum systems are dynamical correlation functions. These correlations are obtained by time-evolving a perturbation of an eigenstate of the system, typically…

Quantum Physics · Physics 2025-02-26 Reinis Irmejs , Raul A. Santos

Monte Carlo studies involving real time dynamics are severely restricted by the sign problem that emerges from highly oscillatory phase of the path integral. In this letter, we present a new method to compute real time quantities on the…

High Energy Physics - Lattice · Physics 2016-08-24 Andrei Alexandru , Gokce Basar , Paulo F. Bedaque , Sohan Vartak , Neill C. Warrington

In this paper, we solve quantum many-body problem by propagating ensembles of trajectories and guiding waves in physical space. We introduce the 'effective potential' correction within the recently proposed time-dependent quantum Monte…

Quantum Physics · Physics 2025-02-05 Ivan P. Christov

We propose a self-contained and accessible derivation of an exact formula for the $n$-point correlation functions of the signal measured when continuously observing a quantum system. The expression depends on the initial quantum state and…

Quantum Physics · Physics 2024-01-10 Pierre Guilmin , Pierre Rouchon , Antoine Tilloy

We obtain an implicit equation for the correlation dimension of dynamical systems in terms of an integral over a propagator. We illustrate the utility of this approach by evaluating the correlation dimension for inertial particles suspended…

Fluid Dynamics · Physics 2015-05-14 Michael Wilkinson , Bernhard Mehlig , Kristian Gustavsson

The work in this paper is four-fold. Firstly, we introduce an alternative approach to solve fractional ordinary differential equations as an expected value of a random time process. Using the latter, we present an interesting numerical…

Dynamical Systems · Mathematics 2022-12-28 Tamer Oraby , Harrinson Arrubla , Erwin Suazo

We consider quantum corrections to classical real time correlation functions at finite temperature. We derive a semi-classical expansion in powers of $\hbar$ with coefficients including all orders in the coupling constant. We give explicit…

High Energy Physics - Theory · Physics 2009-10-30 Dietrich Bödeker

The direct integration of the harmonic oscillator path integral obscures the fundamental structure of its discrete, imaginary time propagator (density matrix). This work, by first proving an operator identity for contracting two free…

Computational Physics · Physics 2023-10-31 Siu A. Chin

Derivation of the procedures that can be applied in evaluating two-time correlation function in terms of coherent-state propagator and corresponding Q-function is presented. On the basis that the involved functions are generally exponential…

Quantum Physics · Physics 2009-10-16 Sintayehu Tesfa

We present an approach to tame the growth of entanglement during time evolution by tensor network methods. It combines time evolution in the complex plane with a perturbative and controlled reconstruction of correlation functions on the…

Strongly Correlated Electrons · Physics 2024-08-26 Xiaodong Cao , Yi Lu , E. Miles Stoudenmire , Olivier Parcollet

We report on an exact calculation of lattice correlation functions on a finite four-dimensional lattice with either Euclidean or Minkowskian signature. The lattice correlation functions are calculated by the method of differential…

High Energy Physics - Theory · Physics 2023-07-12 Federico Gasparotto , Stefan Weinzierl , Xiaofeng Xu

We address the calculation of dynamical correlation functions for many fermion systems at zero temperature, using the auxiliary-field quantum Monte Carlo method. The two-dimensional Hubbard hamiltonian is used as a model system. Although…

Strongly Correlated Electrons · Physics 2016-08-24 Ettore Vitali , Hao Shi , Mingpu Qin , Shiwei Zhang

We evaluate imaginary time density-density correlation functions for a two-dimensional homogeneous electron gas using the phaseless auxiliary field quantum Monte Carlo method. We show that such methodology, once equipped with suitable…

Strongly Correlated Electrons · Physics 2015-09-04 M. Motta , D. E. Galli , S. Moroni , E. Vitali

We propose three physical tests to measure correlations in random numbers used in Monte Carlo simulations. The first test uses autocorrelation times of certain physical quantities when the Ising model is simulated with the Wolff algorithm.…

Condensed Matter · Physics 2009-10-22 I. Vattulainen , T. Ala-Nissila , K. Kankaala

Instanton crystal is a fascinating phase which is encountered when the minimum of the free energy corresponds to a configuration with an imaginary-time-dependent order parameter in the form of a chain of alternating instantons and…

Strongly Correlated Electrons · Physics 2021-11-04 Grigory A. Starkov , Konstantin B. Efetov

A general technique of exact calculation of any correlation functions for the special class of one-dimensional spin models containing small clusters of quantum spins assembled to a chain by alternating with the single Ising spins is…

Statistical Mechanics · Physics 2013-11-05 Stefano Bellucci , Vadim Ohanyan

We present the first direct ab-initio computation of unequal-time correlation functions in non-Abelian lattice gauge theory. We demonstrate non-trivial consistency relations among correlators, time-translation invariance, and agreement with…

High Energy Physics - Lattice · Physics 2025-03-24 Kirill Boguslavski , Paul Hotzy , David I. Müller