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DY: Fachverband Dynamik und Statistische Physik

DY 40: Many-body Quantum Dynamics I (joint session DY/TT)

DY 40.10: Vortrag

Donnerstag, 21. März 2024, 12:00–12:15, A 151

Fluctuations Approach to Quantum Many-Body Systems and its Application to Density Correlations and the Dynamic Structure Factor — •Erik Schroedter, Jan-Philip Joost, and Michael Bonitz — CAU Kiel, Germany

The dynamics of quantum many-body systems following external excitation are of great interest in many areas, such as correlated solids or dense plasmas. Standard approaches used for the description of the dynamics of such systems include the formalisms of reduced density matrices (RDM) and nonequilibrium Green functions (NEGF). However, both approaches are limited in their applicability due to the numerical scaling of simulations with respect to the system size or propagation time. Here, an alternative approach to the dynamics of quantum systems is presented, which is based on fluctuations and their correlation functions [1]. While this new approach is closely related to NEGF and RDM theory [2], it has interesting complementary features, such as the capability to simulate many-body effects using stochastic methods [3,4], which reduce the computational complexity and additionally increase numerical stability for stronger coupling. Moreover, this approach provides direct access to spectral two-particle quantities, such as the density response function or dynamic structure factor, for systems in and far from equilibrium.

[1] E. Schroedter, et al., Cond. Matt. Phys. 25, 23401 (2022)

[2] E. Schroedter, and M. Bonitz, phys. stat. sol. (b) (2024)

[3] D. Lacroix, et al., Phys. Rev. B 90, 125112 (2014)

[4] E. Schroedter, et al., Phys. Rev. B 108, 205109 (2023)

Keywords: nonequilibrium Green functions; quantum fluctuations; stochastic methods; density correlations; dynamic structure factor