Seminar of the Institute for Condensed Matter Physics

# Seminar of the Institute for Condensed Matter Physics

Nonequilibrium dynamical mean-field theory: from strongly correlated materials to ultracold atoms

In this talk I will show how to extend dynamical mean-field theory from the equilibrium to the nonequilibrium regime and will illustrate techniques needed to solve for both the transient response and the steady-state response. The formalism works with the so-called contour-ordered Green's functions on the Kadanoff-Baym-Keldysh contour and requires discretizing continuous matrix operators; the accuracy of the discretization is benchmarked with exact moment sum rules of the local retarded and lesser Green's functions. The computational algorithm is massively parallelizable with the limiting step involving a two-dimensional quadrature of a matrix-valued function. I will illustrate how strongly correlated materials respond to the turning on of a large electric field, which gives rise to damped Bloch oscillations for weak coupling (metals), and more complex "aperiodic" oscillations in the Mott insulator. I will also show how the transient response approaches the steady state. Finally, movies of how particles rearrange themselves in response to a field will be shown, which could be measured in time-of-flight experiments with mixtures of ultracold atoms trapped in optical lattices that are "pulled" in a particular direction.