arXiv subjects

T. P. Simula

Publications and source records attributed to T. P. Simula.

22 records · Page 2Linked to original sources

arXiv2001

Comparison of mean-field theories for vortices in trapped Bose-Einstein condensates

We compute structures of vortex configurations in a harmonically trapped Bose-Einstein condensed atom gas within three different gapless self-consistent mean-field theories. Outside the vortex core region, the density profiles for the condensate and the thermal gas are found to differ only by a few percent between the Hartree-Fock-Bogoliubov-Popov theory and two of its recently proposed gapless extensions. In the core region, however, the differences in the density profiles are substantial. The structural differences are reflected in the energies of the quasiparticle states localized near the vortex core. Especially, the predictions for the energy of the lowest quasiparticle excitation differ considerably between the theoretical models investigated.

cond-mat.soft↗

arXiv2001

Adiabaticity Criterion for Moving Vortices in Dilute Bose-Einstein Condensates

Considering a moving vortex line in a dilute atomic Bose-Einstein condensate within time-dependent Hartree-Fock-Bogoliubov-Popov theory, we derive a criterion for the quasiparticle excitations to follow the vortex core rigidly. The assumption of adiabaticity, which is crucial for the validity of the stationary self-consistent theories in describing such time-dependent phenomena, is shown to imply a stringent criterion for the velocity of the vortex line. Furthermore, this condition is shown to be violated in the recent vortex precession experiments.

cond-mat.stat-mech↗

arXiv2001

Structure and Stability of Vortices in Dilute Bose-Einstein Condensates at Ultralow Temperatures

We compute the structure of a quantized vortex line in a harmonically trapped dilute atomic Bose-Einstein condensate using the Popov version of the Hartree-Fock-Bogoliubov mean-field theory. The vortex is shown to be (meta)stable in a nonrotating trap even in the zero-temperature limit, thus confirming that weak particle interactions induce the condensed gas a fundamental property characterizing ``classical'' superfluids. We present the structure of the vortex at ultralow temperatures and discuss the crucial effect of the thermal gas component to its energetic stability.

cond-mat.soft↗

arXiv2000

Dynamic Scaling in One-Dimensional Cluster-Cluster Aggregation

We study the dynamic scaling properties of an aggregation model in which particles obey both diffusive and driven ballistic dynamics. The diffusion constant and the velocity of a cluster of size $s$ follow $D(s) \sim s^γ$ and $v(s) \sim s^δ$, respectively. We determine the dynamic exponent and the phase diagram for the asymptotic aggregation behavior in one dimension in the presence of mixed dynamics. The asymptotic dynamics is dominated by the process that has the largest dynamic exponent with a crossover that is located at $δ= γ- 1$. The cluster size distributions scale similarly in all cases but the scaling function depends continuously on $γ$ and $δ$. For the purely diffusive case the scaling function has a transition from exponential to algebraic behavior at small argument values as $γ$ changes sign whereas in the drift dominated case the scaling function decays always exponentially.

cond-mat.stat-mech↗