Time dependence of quantum correlation functions

Autor(en)

Ubaldo Bafile, Martin Neumann, Daniele Colognesi, Eleonora Guarini

Abstrakt

In the past few years, the exponential expansion analysis of time autocorrelation functions has provided profound insight into the leading microscopic processes driving the atomic-scale dynamics and has made it possible to highlight the presence and the role of various relaxation channels through which the fundamental correlation functions decay with time. Here we apply this method to the determination of the full time dependence of a correlation function c(t) in a quantum system at nonzero temperature, by making explicit its relationship with its Kubo transform c(K)(t), which in some cases can be approximately computed with the presently available quantum simulation techniques. We obtain an exact expression for c(t) in terms of the exponential modes that describe the time behavior of c(K)(t). The relative importance of the various modes in determining the overall shape of c(t) can then be studied in detail. This work extends to the full time domain the results of a previous paper [Guarini et al., Phys. Rev. Lett. 123, 135301 (2019)], in which we employed the same method to calculate the zero time value of the velocity autocorrelation function, to obtain a microscopic description of the quantum mean kinetic energy in a fluid. In particular, we show that the decay constants and the frequencies of the dominant microscopic modes of c(t) are the same as those of c(K)(t), but the dynamics of the quantum system also contains an additional term decaying on a time scale determined solely by temperature of the system.

Organisation(en)

Computergestützte Physik und Physik der Weichen Materie

Externe Organisation(en)

Consiglio Nazionale delle Ricerche, Università degli Studi di Firenze

Journal

Physical Review E

Band

101

Anzahl der Seiten

12

ISSN

2470-0045

DOI

https://doi.org/10.1103/PhysRevE.101.052110

Publikationsdatum

05-2020

Peer-reviewed

Ja

ÖFOS 2012

103025 Quantenmechanik, 103029 Statistische Physik

Schlagwörter

ASJC Scopus Sachgebiete

Condensed Matter Physics, Statistical and Nonlinear Physics, Statistics and Probability

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/f87fbe3e-f740-4a75-828a-4ea9b2751235