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Molecular electronic spectra can be represented in the time domain as auto-correlation functions of the initial vibrational wavepacket. We present a derivation of the harmonic vibrational auto-correlation function that is valid for both…

Chemical Physics · Physics 2022-10-05 P. Bryan Changala , Nadav Genossar , Joshua H. Baraban

We present an elementary and self-contained account of the analogies existing between classical diffusion and the imaginary-time evolution of quantum systems. These analogies are used to develop a new quantum simulation method which allows…

Condensed Matter · Physics 2007-05-23 S. Baroni , S. Moroni

In this work, we provide a method which allows to compute exactly the multipoint and multi-time correlation functions of a one-dimensional stochastic model of dimer adsorption-evaporation with random (uncorrelated) initial states. In…

Statistical Mechanics · Physics 2016-08-31 Mauro Mobilia

Derivation of two-time second-order correlation function by following approaches such as stochastic differential equation, coherent-state propagator, and quasi-statistical distribution function is presented. In the process, the time…

Quantum Physics · Physics 2024-06-18 Sintayehu Tesfa

We develop an estimator for the correlation function which, in the ensemble average, returns the shape of the correlation function, even for signals that have significant correlations on the scale of the survey region. Our estimator is…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 K. M. Huffenberger , M. Galeazzi , E. Ursino

This paper investigates a new formalism to describe real time evolution of quantum systems at finite temperature. A time correlation function among subsystems will be derived which allows for a probabilistic interpretation. Our derivation…

High Energy Physics - Theory · Physics 2009-10-31 E. Mendel , M. Nest

We emphasize the importance of choosing an appropriate correlation function to reduce numerical errors in calculating the linear-response function as a Fourier transformation of a time-dependent correlation function. As an example we take…

Statistical Mechanics · Physics 2009-10-30 Toshiaki Iitaka

Correlation functions of primordial density fluctuations provide an exciting probe of the physics governing the earliest moments of our Universe. However, the standard approach to compute them is technically challenging. Theoretical…

High Energy Physics - Theory · Physics 2024-09-26 Denis Werth , Lucas Pinol , Sébastien Renaux-Petel

It is well established that causal linear response functions can be found by computing the much simpler imaginary time-ordered Matsubara functions and performing an analytic continuation. This principle is the basis for much of our…

Mesoscale and Nanoscale Physics · Physics 2025-06-27 Sounak Sinha , Barry Bradlyn

After having developed a method that measures real time evolution of quantum systems at a finite temperature, we present here the simplest field theory where this scheme can be applied to, namely the 1+1 Ising model. We will compute the…

High Energy Physics - Theory · Physics 2016-09-06 E. Mendel

It is well known that perturbative solutions of the Langevin equation can be used to calculate correlation functions in stochastic quantization. However, this work is challenging due to the absence of generalized rules. In this paper, we…

High Energy Physics - Theory · Physics 2024-04-03 Moongul Byun

We use the Shadow Wave Function formalism as a convenient model to study the fermion sign problem affecting all projector Quantum Monte Carlo methods in continuum space. We demonstrate that the efficiency of imaginary time projection…

Computational Physics · Physics 2016-05-04 Francesco Calcavecchia , Markus Holzmann

A general approach for derivation of the spectral relations for the multitime correlation functions is presented. A special attention is paid to the consideration of the non-ergodic (conserving) contributions and it is shown that such…

Statistical Mechanics · Physics 2014-02-17 A. M. Shvaika

We develop a highly efficient method to numerically simulate thermal fluctuations and correlations in non-relativistic continuous bosonic one-dimensional systems. The method is suitable for arbitrary local interactions as long as the system…

Quantum Gases · Physics 2020-04-21 Stefan Beck , Igor E. Mazets , Thomas Schweigler

Femtoscopic interferometry is a powerful tool for probing the spatio-temporal evolution of emission sources in heavy-ion collisions. A major challenge in the field is formulating a self-consistent description of the source function,…

Nuclear Theory · Physics 2026-03-11 Sheng Xiao , Yijie Wang , Zhigang Xiao

We propose a method for computing n-time correlation functions of arbitrary spinorial, fermionic, and bosonic operators, consisting of an efficient quantum algorithm that encodes these correlations in an initially added ancillary qubit for…

Quantum Physics · Physics 2014-07-15 J. S. Pedernales , R. Di Candia , I. L. Egusquiza , J. Casanova , E. Solano

A pressing problem in comparing inflationary models with observation is the accurate calculation of correlation functions. One approach is to evolve them using ordinary differential equations ("transport equations"), analogous to the…

Cosmology and Nongalactic Astrophysics · Physics 2012-09-10 David Seery , David J. Mulryne , Jonathan Frazer , Raquel H. Ribeiro

In this and subsequent paper arXiv:1011.5185 we develop a recursive approach for calculating the short-time expansion of the propagator for a general quantum system in a time-dependent potential to orders that have not yet been accessible…

Statistical Mechanics · Physics 2011-08-09 Antun Balaz , Ivana Vidanovic , Aleksandar Bogojevic , Aleksandar Belic , Axel Pelster

We present a general formalism based on scattering theory to calculate quantum correlation functions involving several time-dependent current operators. A key ingredient is the causality of the scattering matrix, which allows one to deal…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 J. Salo , F. W. J. Hekking , J. P. Pekola

We describe and systematically analyze new implementations of the Projection Operator Imaginary Time Spectral Evolution (POITSE) method for the Monte Carlo evaluation of excited state energies. The POITSE method involves the computation of…

Computational Physics · Physics 2007-05-23 Patrick Huang , Alexandra Viel , K. Birgitta Whaley