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200 papers

Recently the general form of a translation-covariant quantum Boltzmann equation has been derived which describes the dynamics of a tracer particle in a quantum gas. We develop a stochastic wave function algorithm that enables full…

Quantum Physics · Physics 2007-09-24 Heinz-Peter Breuer , Bassano Vacchini

We confirm recent claims that, contrary to what was generally believed, the phase transition of the dynamical triangulation model of four-dimensional quantum gravity is of first order. We have looked at this at a volume of 64,000…

High Energy Physics - Lattice · Physics 2009-10-28 Bas V. de Bakker

A continuum model to study the influence of dislocations on the electronic properties of condensed matter systems is described and analyzed. The model is based on a geometrical formalism that associates a density of dislocations with the…

Mesoscale and Nanoscale Physics · Physics 2012-03-22 Fernando de Juan , Alberto Cortijo , María A. H. Vozmediano

This article proposes a weighted-variational model as an approximated surrogate model to lessen numerical complexity and lower the execution times of brittle fracture simulations. Consequently, Monte Carlo studies of brittle fractures…

Materials Science · Physics 2024-03-04 Luis Blanco-Cocom , Marcos A. Capistrán , Jaroslaw Knap , J. Andrés Christen

The dynamics of the discrete Gaussian model for the surface of a crystal deposited on a disordered substrate is investigated by Monte Carlo simulations. The mobility of the growing surface was studied as a function of a small driving force…

Condensed Matter · Physics 2009-10-28 D. Cule

We investigate quantum gravity in four dimensions using the Regge approach on triangulations of the four-torus with general, non-regular incidence matrices. We find that the simplicial lattice tends to develop spikes for vertices with low…

High Energy Physics - Lattice · Physics 2009-10-22 Wolfgang Beirl , Harald Markum , J"urgen Riedler

In this article we study two related models of quantum geometry: generic random trees and two-dimensional causal triangulations. The Hausdorff and spectral dimensions that arise in these models are calculated and their relationship with the…

High Energy Physics - Theory · Physics 2022-11-29 Bergfinnur Durhuus , Thordur Jonsson , John Wheater

Four-dimensional CDT (causal dynamical triangulations) is a lattice theory of geometries which one might use in an attempt to define quantum gravity non-perturbatively, following the standard procedures of lattice field theory. Being a…

High Energy Physics - Theory · Physics 2020-03-19 J. Ambjorn , D. Coumbe , J. Gizbert-Studnicki , A. Görlich , J. Jurkiewicz

We have implemented the dynamical vertex approximation (D$\Gamma$A) in its full parquet-based version to include spatial correlations on all length scales and in {\sl all} scattering channels. The algorithm is applied to study the…

Strongly Correlated Electrons · Physics 2015-06-23 A. Valli , T. Schäfer , P. Thunström , G. Rohringer , S. Andergassen , G. Sangiovanni , K. Held , A. Toschi

We study the properties of the two-dimensional Fermi polaron model in which an impurity attractively interacts with a Fermi sea of particles in the zero-range limit. We use a diagrammatic Monte Carlo (DiagMC) method which allows us to…

Quantum Gases · Physics 2015-06-18 Jonas Vlietinck , Jan Ryckebusch , Kris Van Houcke

We generalize the formalism of the dynamical vertex approximation (D$\Gamma$A) -- a diagrammatic extension of the dynamical mean-field theory (DMFT)-- to treat magnetically ordered phases. To this aim, we start by concisely illustrating the…

Strongly Correlated Electrons · Physics 2021-08-18 Lorenzo Del Re , Alessandro Toschi

We provide a hands-on introduction to Monte Carlo simulations in nonperturbative lattice quantum gravity, formulated in terms of Causal Dynamical Triangulations (CDT). We describe explicitly the implementation of Monte Carlo moves and the…

High Energy Physics - Theory · Physics 2023-10-26 Joren Brunekreef , Andrzej Görlich , Renate Loll

We investigate how exchange-graph techniques can be used to study the topology of strata of meromorphic quadratic differentials. The exchange graph provides natural generators for the fundamental group. By extending the combinatorics of…

Geometric Topology · Mathematics 2026-03-10 Jeonghoon So

We present a new approach to the study of equilibrium properties in many-body quantum physics. Our method takes inspiration from Density Matrix Quantum Monte Carlo and incorporates new crucial features. First of all, the dynamics is…

Quantum Physics · Physics 2022-01-06 Romain Chessex , Massimo Borrelli , Hans Christian Öttinger

In this paper we study in detail, both analytically and numerically, the dynamical properties of the triangle map, a piecewise parabolic automorphism of the two-dimensional torus, for different values of the two independent parameters…

Chaotic Dynamics · Physics 2009-11-13 Martin Horvat , Mirko Degli Esposti , Stefano Isola , Tomaz Prosen , Leonid Bunimovich

We generalize the recently developed diagrammatic Monte Carlo techniques for quantum impurity models from an imaginary time to a Keldysh formalism suitable for real-time and nonequilibrium calculations. Both weak-coupling and…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Philipp Werner , Takashi Oka , Andrew J. Millis

The effects of free surfaces on the dynamic critical behavior of isotropic Heisenberg ferromagnets are studied via phenomenological scaling theory, field-theoretic renormalization group tools, and high-precision computer simulations. An…

Statistical Mechanics · Physics 2009-11-07 M. Krech , H. Karl , H. W. Diehl

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

We discuss the algorithmic problem of minimal coupling gauge fields of the Yang-Mills type to Quantum Gravity in the approach known as Causal Dynamical Triangulations (CDT) as a step towards studying, ultimately, systems of gravity coupled…

High Energy Physics - Lattice · Physics 2021-12-08 Alessandro Candido , Giuseppe Clemente , Massimo D'Elia , Federico Rottoli

I review three different non-perturbative approaches to the three dimensional Thirring model: the 1/N_f expansion, Schwinger-Dyson equations, and Monte Carlo simulation. Simulation results are presented to support the existence of a…

High Energy Physics - Lattice · Physics 2007-05-23 Simon Hands