Two-Time Quantum Fluctuations Approach and its Relation to the Bethe--Salpeter Equation

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Hauptverfasser: Schroedter, Erik, Bonitz, Michael
Format: Preprint
Veröffentlicht: 2023
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author Schroedter, Erik
Bonitz, Michael
author_facet Schroedter, Erik
Bonitz, Michael
contents Correlated quantum many-particle systems out of equilibrium are of high interest in many fields, including correlated solids, ultracold atoms or dense plasmas. Accurate theoretical description of these systems is challenging both, conceptionally and with respect to computational resources. We have recently presented a quantum fluctuations approach which is equivalent to the nonequilibrium $GW$ approximation [E. Schroedter \textit{et al.}, Cond. Matt. Phys. \textbf{25}, 23401 (2022)] that promises high accuracy at low computational cost. In a second publication [E. Schroedter \textit{et al.}, Phys. Rev. B \textbf{108}, 205109 (2023)], this approach was extended to the two-time exchange-correlation functions and the density response properties. Here, we analyze the properties of this approach in more detail. We demonstrate that the method is equivalent to the Bethe--Salpeter equation for the two-time exchange-correlation function when the generalized Kadanoff-Baym ansatz with Hartree-Fock propagators is applied.
format Preprint
id arxiv_https___arxiv_org_abs_2312_15034
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Two-Time Quantum Fluctuations Approach and its Relation to the Bethe--Salpeter Equation
Schroedter, Erik
Bonitz, Michael
Strongly Correlated Electrons
Plasma Physics
Quantum Physics
Correlated quantum many-particle systems out of equilibrium are of high interest in many fields, including correlated solids, ultracold atoms or dense plasmas. Accurate theoretical description of these systems is challenging both, conceptionally and with respect to computational resources. We have recently presented a quantum fluctuations approach which is equivalent to the nonequilibrium $GW$ approximation [E. Schroedter \textit{et al.}, Cond. Matt. Phys. \textbf{25}, 23401 (2022)] that promises high accuracy at low computational cost. In a second publication [E. Schroedter \textit{et al.}, Phys. Rev. B \textbf{108}, 205109 (2023)], this approach was extended to the two-time exchange-correlation functions and the density response properties. Here, we analyze the properties of this approach in more detail. We demonstrate that the method is equivalent to the Bethe--Salpeter equation for the two-time exchange-correlation function when the generalized Kadanoff-Baym ansatz with Hartree-Fock propagators is applied.
title Two-Time Quantum Fluctuations Approach and its Relation to the Bethe--Salpeter Equation
topic Strongly Correlated Electrons
Plasma Physics
Quantum Physics
url https://arxiv.org/abs/2312.15034