Quantum gases with competing interactions

Quantum degenerate mixtures of potassium isotopes display broadly tunable interatomic interactions in both Bose-Bose and Bose-Fermi mixtures. In the potassium lab, we explore the broad spectrum of new possibilities that this opens for the quantum simulation of continuum systems. Mixtures of Bose-Einstein condensates allow us to realize novel types of ultradilute quantum liquids that are stabilized by quantum fluctuations and do not fit into the standard Van der Waals picture of liquids. Adding an optical coupling, we engineer artificial gauge fields that feature a back-action from matter and simulate gauge theories analogous to those used to describe fractional quantum Hall states. Very recently, we have observed in the same system a supersolid gas: an antithetic quantum phase of matter that combines the frictionless flow of a superfluid with the crystalline structure of a solid. In the future, we aim to investigate other unconventional superfluid phases: supersolid liquids, topological superfluids, and many other intriguing many-body states of matter.