2016/08/31 by Vladimir Veljić, Vladimir Veljic, Antun Balaž +2
Physics and Astronomy · #Atomic and Subatomic Physics Research #Boltzmann constant #Boltzmann equation #Classical mechanics #Cold Atom Physics and Bose-Einstein Condensates #Dipole #Ellipsoid #Fermi Gamma-ray Space Telescope #Physics #Quantum electrodynamics #Quantum mechanics #Relaxation (psychology) #Scaling #Statistical physics #Strong Light-Matter Interactions #cond-mat.quant-gas #physics.comp-ph #quant-ph
paper · pdf · doi:10.1103/physreva.95.053635
published as Phys. Rev. A 95, 053635 (2017) · 19 pages, 12 figues
openalex created_date 2016/09/16 · openalex publication_date 2017/05/26 · arxiv created 2017/05/27 · arxiv updated 2017/05/30 · openalex updated_date 2026/08/05
A recent time-of-flight (TOF) expansion experiment with polarized fermionic erbium atoms measured a Fermi surface deformation from a sphere to an ellipsoid due to dipole-dipole interaction, thus confirming previous theoretical predictions. Here we perform a systematic study of the ground-state properties and TOF dynamics for trapped dipolar Fermi gases from the collisionless to the hydrodynamic regime at zero temperature. To this end, we solve analytically the underlying Boltzmann-Vlasov equation within the relaxation-time approximation in the vicinity of equilibrium by using a suitable rescaling of the equilibrium distribution. The resulting ordinary differential equations for the respective scaling parameters are then solved numerically for experimentally realistic parameters and relaxation times that correspond to the collisionless, collisional, and hydrodynamic regimes. The equations for the collisional regime are first solved in the approximation of a fixed relaxation time, and then this approach is extended to include a self-consistent determination of the relaxation time. The presented analytical and numerical results are relevant for a detailed quantitative understanding of ongoing experiments and the design of future experiments with ultracold fermionic dipolar atoms and molecules. In particular, the obtained results are relevant for systems with strong dipole-dipole interaction, which turn out to affect significantly the aspect ratios during the TOF expansion.