13 research outputs found
Quantum degenerate dipolar Fermi gas
The interplay between crystallinity and superfluidity is of great fundamental
and technological interest in condensed matter settings. In particular,
electronic quantum liquid crystallinity arises in the non-Fermi liquid,
pseudogap regime neighboring a cuprate's unconventional superconducting phase.
While the techniques of ultracold atomic physics and quantum optics have
enabled explorations of the strongly correlated, many-body physics inherent in,
e.g., the Hubbard model, lacking has been the ability to create a quantum
degenerate Fermi gas with interparticle interactions---such as the strong
dipole-dipole interaction---capable of inducing analogs to electronic quantum
liquid crystals. We report the first quantum degenerate dipolar Fermi gas, the
realization of which opens a new frontier for exploring strongly correlated
physics and, in particular, the quantum melting of smectics in the pristine
environment provided by the ultracold atomic physics setting. A quantum
degenerate Fermi gas of the most magnetic atom 161Dy is produced by laser
cooling to 10 uK before sympathetically cooling with ultracold, bosonic 162Dy.
The temperature of the spin-polarized 161Dy is a factor T/TF=0.2 below the
Fermi temperature TF=300 nK. The co-trapped 162Dy concomitantly cools to
approximately Tc for Bose-Einstein condensation, thus realizing a novel, nearly
quantum degenerate dipolar Bose-Fermi gas mixture.Comment: 6 pages, 3 figure
A long-lived spin-orbit-coupled degenerate dipolar Fermi gas
We describe the creation of a long-lived spin-orbit-coupled gas of quantum
degenerate atoms using the most magnetic fermionic element, dysprosium.
Spin-orbit-coupling arises from a synthetic gauge field created by the
adiabatic following of degenerate dressed states comprised of optically coupled
components of an atomic spin. Because of dysprosium's large electronic orbital
angular momentum and large magnetic moment, the lifetime of the gas is limited
not by spontaneous emission from the light-matter coupling, as for gases of
alkali-metal atoms, but by dipolar relaxation of the spin. This relaxation is
suppressed at large magnetic fields due to Fermi statistics. We observe
lifetimes up to 400 ms, which exceeds that of spin-orbit-coupled fermionic
alkali atoms by a factor of 10-100, and is close to the value obtained from a
theoretical model. Elastic dipolar interactions are also observed to influence
the Rabi evolution of the spin, revealing an interacting fermionic system. The
long lifetime of this weakly interacting spin-orbit-coupled degenerate Fermi
gas will facilitate the study of quantum many-body phenomena manifest at longer
timescales, with exciting implications for the exploration of exotic
topological quantum liquids.Comment: 11 pages, 8 figures, one appendi
Anisotropic expansion of a thermal dipolar Bose gas
We report on the anisotropic expansion of ultracold bosonic dysprosium gases
at temperatures above quantum degeneracy and develop a quantitative theory to
describe this behavior. The theory expresses the post-expansion aspect ratio in
terms of temperature and microscopic collisional properties by incorporating
Hartree-Fock mean-field interactions, hydrodynamic effects, and
Bose-enhancement factors. Our results extend the utility of expansion imaging
by providing accurate thermometry for dipolar thermal Bose gases, reducing
error in expansion thermometry from tens of percent to only a few percent.
Furthermore, we present a simple method to determine scattering lengths in
dipolar gases, including near a Feshbach resonance, through observation of
thermal gas expansion.Comment: main text and supplement, 11 pages total, 4 figure