Erbium Experiment:
Topology with Ultracold Atoms

In 2017, as the second group worldwide, we have observed Bose-Einstein condensation of this rare earth element. In current work, we aim at the observation of novel topological matter with the cold erbium atomic gas system and for this create synthetic magnetic fields by Raman manipulation. Specifically, we both aim at the observation of fractional quantum Hall physics as well as the realization of parafermions, i.e. fractional Majoranas, with our bosonic erbium atoms.

In recent experimental work, we have realized synthetic quantum Hall system with the erbium atoms being in the lowest Landau level. The experiment builds upon earlier work in synthetic quantum Hall systems with other species. The quantum Hall geometry is realized in the two-dimensional state space of one internal and one synthetic dimension. We experimentally observe distinct bulk and edge behavior in the Hall drift. We also have determined the local Chern number and furthermore we have observed chiral edge currents.

© AG Weitz

A view into the vacuum chamber shows the atom cloud trapped in a magneto-optical trap as a yellow cloud in the center.

Some insights

© AG Weitz

A view at the table: The optics close to the vacuum chamber in the top left corner is used to guide the light to the erbium atoms.

© AG Weitz

With our setup, we were able to observe "skipping orbits" at the edges of a synthetic Hall system, realized by real space and artificial dimensions. 

© H. Brammer/U Bonn

Due to the rich level structure, erbium atoms can also be trapped in a blue MOT.

Latest Paper

Chiral edge dynamics of cold erbium atoms in the lowest Landau level of a synthetic quantum Hall system
R. V. Roell, A. Warsi Laskar, F. R. Huybrechts, M. Weitz

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