BoDy Lab

In our lab, we exploit dysprosium's special electronic and magnetic properties to unveil novel quantum phenomena in ultracold atomic assemblies.

Dysprosium is one of the most magnetic elements in the periodic table. The large magnetic dipole moment of dysprosium atoms in their ground state induces large interatomic dipolar interactions. The long-range and anisotropic nature of the dipolar interactions distinguishes them from the more conventional contact interactions that usually prevails in ultracold atomic gases. The introduction of dipolar interactions interaction and its competition with the contact interaction brings an interesting new twist to the physics of the quantum fluids made up of these atoms. In recent years, this has led to the discovery of new phases of matter, including ultradilute quantum droplets, droplet crystals and supersolids.

Our BoDy experiment is a new-generation apparatus that creates and probes degenerate quantum gases of bosonic dysprosium atoms with exquisite control. Using an accordion lattice setup, we can change the dimensionality of the gas from htree-dimensionnal to lower dimensions and especially to two-dimensional. Using a digital micromirror device, we can create traps with tailorable and dynamically tunable geometries in plane. Using a set of small magnetic field coil pairs, we are able to tune the magnitude and direction of the external magnetic field. We thus control the interparticle interactions, namely the strength of the contact interactions and the direction of the dipoles. Finally, our high-NA microscope objective allow us to probe the atomic cloud dnesity distribution with sub-micron resolution.

The design of our experiment is based on a novel slowing and cooling scheme for Dy atoms, where a 2D magneto-optical trap (MOT) operating on the broad transition of Dy at 421 nm directly loads a 3D MOT operating on the 136 kHz wide intercombination line at 626 nm in the center of our science chamber. This design allows for a compact setup with still significant optical access around the science chamber. This novel scheme was particularly successful and its demonstration and characterization was the subject of the first experimental paper from our lab. If you are interested, you can find it here! Based on this first cooling stage, we were able to efficiently load a crossed optical dipole operating at 1064 nm and perform evaporative cooling down to quantum degeneracy, achieving a Bose-Einstein condensate of 1.5x10^5 atoms with more than 70% condensed fraction.

Focussing on a surf-board trap shape, we have recently obtained our first in-situ and time-of-flight images of supersolid and insulating crystal states, relying on high and low intensity absorption imaging on the 421nm trnasition respectively. The geoemtry of the underlying crystal is two-dimensional. By tuning the interaction parameters, we observe the transition between different crystal structures. We are currently investigating this transition experimentally and theoretically.