Dresden 2017 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 19: Poster Session: Correlated Electrons 1

TT 19.61: Poster

Montag, 20. März 2017, 15:00–19:00, P2-EG

Emergence of hydrodynamic long-time tails from noisy Boltzmann equations — •Philipp Weiß, Jonathan Lux, and Achim Rosch — Institute for Theoretical Physics, University of Cologne, Germany

When an interacting quantum system undergoes a quantum quench, we expect that the system will ultimately reach thermal equilibrium. Local equilibrium is established by scattering of quasiparticles on intermediate time scales. However, global equilibration requires diffusive transport of conserved quantities resulting in a slow algebraic relaxation towards thermal equilibrium. Phenomenologically, the final state of the relaxation can be described by fluctuating hydrodynamics. But, how does this irreversible dynamics emerge from the unitary time-evolution of a closed quantum system?

Here, we address this question within a quantum-kinetic approach. Even on the level of the Boltzmann equation an additional noise term is required to reproduce the algebraic long-time behavior. In a first step, we show that fluctuating hydrodynamics can be derived from the fluctuating Boltzmann equation. Similarly, we aim to derive a “noisy quantum-Boltzmann equation” which mimics the hydrodynamic fluctuations on the quantum level. A possible derivation starts from a modified Keldysh-Dyson equation, supplemented by a noise term. Such an equation defines a noise-dependent Green’s function. Following this route, we have to ensure that averaging of “noisy Green’s functions” reproduces the exact higher-order correlation functions.