Our research focuses on ultracold strongly magnetic Lanthanides for realizing dipolar quantum matter. Lanthanides are a novel and powerful resource for accessing quantum many- and few-body physics because of their extremely rich atomic level spectra and their highly anisotropic interaction potentials. Our goal is to study the fascinating effects emerging from the dipole-dipole interaction and the anisotropic short-range van der Waal interaction at the interface between condensed matter, atomic and molecular physics.
We have two experimental apparatuses. The ERBIUM machine operates on Er atoms and produced the first Er Bose-Einstein condensate and degenerate Fermi gas. The RARE machine is currently under construction and aims at combining two different lanthanides: Er and Dy.
Why Er and Dy?
Erbium and dysprosium offer unique combination of desirable properties for quantum gas experiments.
- Several stable isotopes: Among the five bosonic isotopes there are three abundant ones (>15%) for Er, whereas 2 abundant ones for Dy, well suited for trapping a large number of atoms. The fermionic isotopes 167Er, 161Dy and 163Dy have a remarkably abundance as compared to other fermionic systems. This richness in isotopes will also lead to a corresponding richness in the scattering properties, regarding the sign and magnitude of the background scattering lengths and the character of Feshbach resonances.
- Large atomic mass: Many relevant energies in the system, such as the recoil energy and the mean field energy will be reduced by the large mass of Er and Dy. As heavy atoms, they are expected to show very rich interactions properties. The collisional physics will be, for instance, enriched by strong spin-orbit contributions and a large orbital angular momentum in the ground state, which provides a scenario never considered in ultracold collisional physics.
- Strong magnetic character: Between the laser-cooled species, erbium and dysprosium have the strongest magnetic moment with 7µB and 10µB, respectively. Simple arguments, based on large Zeeman shifts and strong spin-orbit interactions, let us expect the appearance of many Feshbach resonances in a relatively narrow magnetic field range. The large magnetic moment in combination with the large mass leads to a particularly strong dipolar character.