arXiv subjects

A. L. Fetter

Publications and source records attributed to A. L. Fetter.

4 recordsLinked to original sources

arXiv2016

Spin-orbit-coupled Bose-Einstein-condensed atoms confined in annular potentials

A spin-orbit-coupled Bose-Einstein-condensed cloud of atoms confined in an annular trapping potential shows a variety of phases that we investigate in the present study. Starting with the non-interacting problem, the homogeneous phase that is present in an untrapped system is replaced by a sinusoidal density variation in the limit of a very narrow annulus. In the case of an untrapped system there is another phase with a striped-like density distribution, and its counterpart is also found in the limit of a very narrow annulus. As the width of the annulus increases, this picture persists qualitatively. Depending on the relative strength between the inter- and the intra-components, interactions either favor the striped phase, or suppress it, in which case either a homogeneous, or a sinusoidal-like phase appears. Interactions also give rise to novel solutions with a nonzero circulation.

cond-mat.quant-gas↗

arXiv2004

Oscillations of a Bose-Einstein condensate rotating in a harmonic plus quartic trap

We study the normal modes of a two-dimensional rotating Bose-Einstein condensate confined in a quadratic plus quartic trap. Hydrodynamic theory and sum rules are used to derive analytical predictions for the collective frequencies in the limit of high angular velocities, $Ω$, where the vortex lattice produced by the rotation exhibits an annular structure. We predict a class of excitations with frequency $\sqrt{6} Ω$ in the rotating frame, irrespective of the mode multipolarity $m$, as well as a class of low energy modes with frequency proportional to $|m|/Ω$. The predictions are in good agreement with results of numerical simulations based on the 2D Gross-Pitaevskii equation. The same analysis is also carried out at even higher angular velocities, where the system enters the giant vortex regime.

cond-mat.stat-mech↗

arXiv1995

Vortex State in a d-Wave Superconductor

We discuss the physics of the vortex state in a $d$-wave superconductor, using the phenomenological Ginzburg-Landau theory, where many novel phenomena arise from the small admixture of the $s$-wave component induced by spatial variations in the dominant $d$-wave. Properties of an isolated vortex and of the Abrikosov vortex lattice are studied by means of analytic and numerical methods. An isolated vortex has a considerable structure, with four ``extra'' nodes in the $s$-wave order parameter symmerically placed around the core and an amplitude forming a four-lobe profile decaying as $1/r^2$ at large distances. The supercurrent and magnetic field distributions are also calculated. The Abrikosov lattice is in general oblique with the precise shape determined by the magnetic field and $s$-$d$ mixing parameter $ε_v$. The magnetic field distribution in the Abrikosov state has two nonequivalent saddle points resulting in the prediction of a double peak line shape in $μ$SR and NMR experiments as a test of a $d$-wave symmetry. Detailed comparison is made with existing experimental data and new experiments are proposed to test for the predicted effects.

cond-mat↗

arXiv1995

GINZBURG-LANDAU THEORY OF VORTICES IN $d$-WAVE SUPERCONDUCTORS

Ginzburg-Landau theory is used to study the properties of single vortices and of the Abrikosov vortex lattice in a $d_{x^2-y^2}$ superconductor. For a single vortex, the $s$-wave order parameter has the expected four-lobe structure in a ring around the core and falls off like $1/r^2$ at large distances. The topological structure of the $s$-wave order parameter consists of one counter-rotating unit vortex, centered at the core, surrounded by four symmetrically placed positive unit vortices. The Abrikosov lattice is shown to have a triangular structure close to $T_c$ and an oblique structure at lower temperatures. Comparison is made to recent neutron scattering data.

cond-mat↗