Supersolids and beyond: exploring new states of matter with laser-cooled dipolar molecules
Quantum mechanics becomes most fascinating when its counterintuitive phenomena are observable on a macroscopic scale. The goal of this project is to realize and study novel states of matter that are paradigmatic examples of such behaviour.

My primary focus is the paradoxical supersolid state of matter, which combines the crystal structure of a solid with the frictionless flow of a superfluid. The very existence of this state has been debated intensively for over 60 years. After decades of inconclusive efforts in helium, I have recently observed evidence for this state in magnetic quantum gases. This discovery has raised a plethora of new questions, which can be addressed with neither magnetic atoms nor helium, and thus require fundamentally new experimental approaches.

In this project I will use laser-cooled dipolar molecules to explore supersolidity far beyond the state of the art. Starting from an ultracold gas of molecules, I will study - from few to many-body - long-discussed scenarios for supersolidity. The use of flexible optical potentials will allow me to investigate the role of doping, defects, dimensionality and disorder on the formation and dynamics of a supersolid. By using high-resolution, single-molecule imaging, I will be able to follow the corresponding dynamics down to the most elementary level, where correlations and entanglement become accessible.

A particular significant generalization of this scenario arises when the spatial ordering competes with magnetic ordering. The molecules employed exhibit both electric and magnetic dipole moments and thus naturally feature the additional degree of freedom required to realize spin models. This will enable studying further exotic states of matter in which topological effects are expected to emerge.

The extraordinary clean and tunable experimental approach will facilitate a precise comparison with theory, and thus promises unprecedented insights into the nature of these new states of matter.