Time dependence of quantum correlation functions
- Author(s)
- Ubaldo Bafile, Martin Neumann, Daniele Colognesi, Eleonora Guarini
- Abstract
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(s)
- Computational and Soft Matter Physics
- External organisation(s)
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", CNR, University of Florence
- Journal
- Physical Review E
- Volume
- 101
- No. of pages
- 12
- ISSN
- 2470-0045
- DOI
- https://doi.org/10.1103/PhysRevE.101.052110
- Publication date
- 05-2020
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103025 Quantum mechanics, 103029 Statistical physics
- Keywords
- ASJC Scopus subject areas
- Condensed Matter Physics, Statistical and Nonlinear Physics, Statistics and Probability
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/time-dependence-of-quantum-correlation-functions(f87fbe3e-f740-4a75-828a-4ea9b2751235).html