Supersolidity and New Quantum Liquids in the Lee-Huang-Yang regime

Recent experiments with ultra-cold atomic quantum gases of dipolar dysprosium or erbium atoms reported new evidence for the long-sought supersolid state of matter, combining superfluidity with periodic density modulations.

Intriguingly, these novel states are stabilized by the Lee-Huang-Yang (LHY) quantum fluctuation corrections that usually are by far too weak to play a significant role, but here can be brought into a balance with a weak residual mean-field.

Similarly, trapped binary ultra-cold gases of alkali atoms may be tuned such that the mean-field vanishes exactly, and quantum fluctuations prevail, forming a so-called “pure” LHY liquid.

These novel types of quantum matter have very peculiar properties challenging our present understanding of many-body quantum systems.

The project sets the focus on their theoretical analysis and numerical modeling: We aim to investigate flow and the onset of dissipation when stirring a toroidal dipolar supersolid with a rotating barrier, study supersolid flow through a capillary tube, and investigate supersolidity and drag in dipolar mixtures.

We will explore the pure LHY liquid, where novel pattern formations and surface wave instabilities are revealed.

Finally, we address the challenging regime between the few- and many-body limit, with the aim to gain insight into arising elementary excitation modes signaling the build-up of quantum phase transitions.