Corinna Kollath (University of Bonn, Germany)

Spreading of correlations in strongly correlated (dissipative) quantum gases

Atomic gases cooled to Nanokelvin temperatures are a new exciting tool to
study a broad range of quantum phenomena. In particular, an outstanding and rapid
control over the fundamental parameters, such as interaction
strength, spin composition, and dimensionality allows to realize and observe many
different situations far from equilibrium. One of the fundamental questions is the
spreading of correlations under the change of a parameter of the system as e.g. the
interaction strength. In one-dimensional systems often the correlations are carried by
quasi-particle excitations which propagate almost ballistically through the system. We
will present results of such a propagation after an abrupt parameter change in
comparison with experimental results. We extend the investigation to a slow change of a
parameter where the spreading dynamics takes a generalized ‘light-cone’ form. Further,
I will contrast the spreading in an isolated system to the spreading in systems
subjected to dissipative couplings. One focus will be the question of how in a
repulsively interacting fermionic gas, coherence between pairs of fermions can emerge
by local coupling to an incoherent environment. The numerical results are obtained with
the time-dependent density matrix renormalization group (or matrix product state)
methods and the application to dissipative systems will be outlined.