Controlling and Understanding of Dipolar Quantum Gases of Erbium Atoms

@article{PatscheiderPhD,
  title = {Controlling and Understanding of Dipolar Quantum Gases of Erbium Atoms},
  author = {Patscheider, Alexander},
  journal = {PhD Thesis},
  year = {2022},
  month = {Apr},
  abstract = {In recent decades, great progress has been made in the realization of various atomic, molecular,
and optical physics (AMO) platforms to study quantum mechanical many-body phenomena,
e. g. atomic and molecular quantum gases [Blo12, Gro17], trapped ions [Bla12, Hem18],
and Rydberg atoms in optical tweezers [Ber17, Bro20]. Atomic quantum gases offer a powerful
collection of desirable properties: tunability of interactions, geometry, and statistics
(bosonic/fermionic), the manipulation of the internal degree of freedom (spin), and an intrinsic
scalability of the system size. Additionally, their high environmental isolation makes
them attractive for fundamental research as well as promising candidates for various technological
applications.
As progress has advanced, new ideas have emerged about the possibility of quantum simulating
a variety of phases of matter, or even creating some that have no counterpart in other
systems. Some of these exciting proposals required a radical change in the nature of the
interaction that governs the many-body behavior. From the traditional
”short-range“ interaction,
whose strength is appealing because of its tunability, the proposals started to focus on
platforms in which the atoms interact via a long-range potential that activates a connection
between atoms over a long distance. Platforms such as ultracold molecules, Rydberg atoms,
cavity-mediated systems, and magnetic atoms started to appear on the experiment map.
This thesis focuses on a new class of magnetic quantum gases consisting of magnetic lanthanides,
which are gaining a remarkable momentum in the scientific community due to
their extraordinarily large magnetic dipole moment. In erbium and dysprosium, the magnetic
interaction is a factor > 100 larger than in alkali atoms and several times larger than in
transition metals. Our group has pioneered this field with the first Bose-Einstein condensate
of erbium [Aik12], now celebrating its 10th anniversary, and with the observation of novel
phenomena such as roton modes [Cho18, Pet19] and supersolidity [B¨ot19b, Tan19, Cho19].
Within this thesis, we present our progress in increasing the level of control over these new
systems, based on the special properties of lanthanides. We realize a quantum simulator for
the XXZ-Heisenberg model with large spins in a three-dimensional optical lattice and study
magnetization conserving spin-exchange dynamics. The large spin manifold is encoded in
the 20 Zeeman levels associated with the atomic ground state of fermionic erbium. We
demonstrate experimental control over the rate at which the dynamics occur by changing
the initial spin state, by tuning the dipole orientation, or by exploiting ac-Stark shifts to
alter the resonance condition.
To obtain enhanced control over the internal atomic states, we extend our experimental
toolbox with a narrow optical transition at 1299 nm, with a spectral linewidth on the order of
only 1 Hz. We perform a detailed characterization of the fundamental transition parameters,
such as lifetime, isotope shifts, and Land´e gJ -factor. Studies of the dynamic polarizability
of the excited state with respect to the ground state open up interesting opportunities for
magic-wavelength lattices and other exciting applications.
Finally, we expand our understanding on the collision properties of dipolar atoms and study
thermalization dynamics of cold, non-degenerate quantum gases. Within this work, we apply the cross-dimensional thermalization technique to gain knowledge on the contact scattering
length for four bosonic isotopes over a broad magnetic field range. This also allows us to
extract a background scattering length for each isotope and analyze its scaling with the
isotope mass. Since theoretical calculations of the scattering length for complex magnetic
atoms are very challenging, our results represent a valuable contribution for the development
of advanced theoretical models.},
  url = {http://www.erbium.at/FF/wp-content/uploads/2022/11/Dissertation_Alexander_Patscheider.pdf},
}