FewBoDyK

This project proposed by a consortium of experimental and theoretical partners, aims to tackle the few-body problem in an ultracold gas of "complex" atoms, specifically lanthanides. Due to the very large magnetic dipolar couplings present in these fluids, their properties differ starkly from those of well-known alkali metal gases. The precise adjustment of pair-wise interactions through external magnetic field scanning reveals a high density of scattering resonances whose origins are not yet fully comprehended, and whose modeling thus far relies on tools from random matrix theory. Our first objective is to experimentally characterize these resonances on a novel platform, and interpret them with a combination of precise computation of long-range interactions combined to parametric short-range interactions implemented in our in-house developed scattering code. We will start by deciphering the interplay between two-body and three-body physics for a polarized gas, and then expand our investigations to the unpolarized case, where more collision channels are available. This comprehension is vital for the integration of spin-orbit coupling in lanthanide gases. Finally, we will expand our study of the few-body problem to a mixture of dysprosium and potassium. By capitalizing on a particular confinement geometry, our objective is to predict and observe novel (stable!) Dy2K trimers, resulting from the combination of dipolar Dy–Dy interactions and the binding provided by the K atom. Such trimers can be viewed as relatives to the (short-lived!) Efimov trimers predicted in nuclear physics and observed with cold atoms. The added value of the project lies in combining high-precision measurements and state-of-the-art numerical calculations to identify the main underlying laws that govern the interactions within these gases. This research will lay the groundwork for exploring new phases of quantum matter with novel composite objects.