B3: Ultracold quantum gases in spatially and temporally engineered environments

Corinna Kollath & Herwig Ott

In the combined theoretical and experimental project B3 we will investigate the influence of spatially and temporally engineered dissipative environments onto interacting Bose gases. The rich properties of interacting quantum gases are characterized by the competition of the interaction energy, the potential energy and the kinetic energy. The dissipative coupling to an environment is a new competitor to these coherent processes which has strong impact on the steady states and the dynamics of the many-body quantum system.  The experimental realization uses a rubidium quantum gas experiment, where local losses are implemented via a focused electron beam and local potential modulations are generated via overlapped repulsive and attractive miniaturized dipole traps. Theoretically, we model these systems either within a Lindblad master equation or a (non-)hermitian Hamiltonian description using an interacting Bose gas. We have shown in the first funding period that many exciting transport properties are induced by local and global time-independent dissipation. Examples for this include coherent perfect absorption of matter waves and the drastically changed propagation of correlations. Extending the studies of the first funding period, we will shift towards time-modulated dissipation and potentials. These have the potential to induce new transport effects and meta-stable bound states. We expect that the inclusion of time-modulated drive will allow us to explore resonance phenomena, thus maximizing the desired engineering task while minimizing global losses and heating effects.

A local dissipative defect is created by an electron beam in an ultracold Bose gas confined to an optical lattice potential.