NQO Lecture: Dipolar quantum liquids

Who: Igor Ferrier-Barbut (Universität Stuttgart)
When: Thursday, June 21, 2018 at 16:00
Where: The CP³ meeting room

Dilute, ultracold samples of lanthanide atoms have emerged as a promising new research frontier. Their strong magnetic moment indeed allows to study the consequences of long-range anisotropic dipole-dipole interactions in a quantum many-body system. Experiments benefit from the control tools of ultracold atomic physics allowing to characterize few-body effects and to isolate the key many-body mechanisms. In recent years, manifestations of dipolar interactions have been observed in Bose-Einstein condensates, Mott insulators and Fermi seas.
In these systems one can reach the regime where dipolar interactions dominate over usual short-range interactions of van der Waals origin. I this talk I will present our experimental results on magnetic quantum fluids made out of a Bose-Einstein condensate of dysprosium atoms. Striking effects of magnetic interactions can be observed, such as a strong anisotropy in superfluid flow properties. We have in particular discovered a phase-transition between a gas and a liquid, characterized by the formation of a many-body bound state. The liquid owes its stability to quantum fluctuations of the fluid’s collective modes, and the same mechanism is relevant for other seemingly unrelated systems where similar liquid phases can be reached, defining a new class of ultra-dilute quantum liquids.