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Rotational Fluxons of Bose-Einstein Condensates in Coplanar Double-Ring Traps  [PDF]
J. Brand,T. J. Haigh,U. Zülicke
Physics , 2008, DOI: 10.1103/PhysRevA.80.011602
Abstract: Rotational analogs to magnetic fluxons in conventional Josephson junctions are predicted to emerge in the ground state of rotating tunnel-coupled annular Bose-Einstein condensates (BECs). Such topological condensate-phase structures can be manipulated by external potentials. We determine conditions for observing macroscopic quantum tunneling of a fluxon. Rotational fluxons in double-ring BECs can be created, manipulated, and controlled by external potential in different ways than possible in the solid state system, thus rendering them a promising new candidate system for studying and utilizing quantum properties of collective many-particle degrees of freedom.
Anomalous modes drive vortex dynamics in confined Bose-Einstein condensates  [PDF]
David L. Feder,Anatoly A. Svidzinsky,Alexander L. Fetter,Charles W. Clark
Physics , 2000, DOI: 10.1103/PhysRevLett.86.564
Abstract: The dynamics of vortices in trapped Bose-Einstein condensates are investigated both analytically and numerically. In axially symmetric traps, the critical rotation frequency for the metastability of an isolated vortex coincides with the largest vortex precession frequency (or anomalous mode) in the Bogoliubov excitation spectrum. As the condensate becomes more elongated, the number of anomalous modes increases. The largest frequency of these modes exceeds both the thermodynamic critical frequency and the nucleation frequency at which vortices are created dynamically. Thus, anomalous modes describe not only the critical rotation frequency for creation of the first vortex in an elongated condensate but also the vortex precession in a single-component spherical condensate.
Bose--Einstein solitons in highly asymmetric traps  [PDF]
Victor M. Perez-Garcia,H. Michinel,H. Herrero
Physics , 1998, DOI: 10.1103/PhysRevA.57.3837
Abstract: We obtain analytic solutions to the Gross-Pitaevskii equation with negative scattering length in highly asymmetric traps. We find that in these traps the Bose--Einstein condensates behave like quasiparticles and do not expand when the trapping in one direction is eliminated. The results can be applicable to the control of the motion of Bose--Einstein condensates.
Rotational Response of Two-Component Bose-Einstein Condensates in Ring Traps  [PDF]
P. L. Halkyard,M. P. A. Jones,S. A. Gardiner
Physics , 2010, DOI: 10.1103/PhysRevA.81.061602
Abstract: We consider a two-component Bose-Einstein condensate (BEC) in a ring trap in a rotating frame, and show how to determine the response of such a configuration to being in a rotating frame, via accumulation of a Sagnac phase. This may be accomplished either through population oscillations, or the motion of spatial density fringes. We explicitly include the effect of interactions via a mean-field description, and study the fidelity of the dynamics relative to an ideal configuration.
Stability of Bose-Einstein Condensates Confined in Traps  [PDF]
Takeya Tsurumi,Hirofumi Morise,Miki Wadati
Physics , 1999, DOI: 10.1142/S0217979200000595
Abstract: Bose-Einstein condensation has been realized in dilute atomic vapors. This achievement has generated immerse interest in this field. Presented is a review of recent theoretical research into the properties of trapped dilute-gas Bose-Einstein condensates. Among them, stability of Bose-Einstein condensates confined in traps is mainly discussed. Static properties of the ground state are investigated by use of the variational method. The anlysis is extended to the stability of two-component condensates. Time-development of the condensate is well-described by the Gross-Pitaevskii equation which is known in nonlinear physics as the nonlinear Schr\"odinger equation. For the case that the inter-atomic potential is effectively attractive, a singularity of the solution emerges in a finite time. This phenomenon which we call collapse explains the upper bound for the number of atoms in such condensates under traps.
Rotating Atomic Traps for Bosons and the Centrifuge Effect  [PDF]
T. Majmudar,A. Widom
Physics , 2000,
Abstract: A rigorous time independent Hamiltonian for rotating atomic traps is discussed. The steady states carry a mass current and thereby an angular momentum. It is shown that the rotation positions the atoms away from the rotation axis (after taking both the time and quantum mechanical averages) as in a conventional centrifuge. Some assert that the rotation for Bose condensates cause the atoms to move towards the rotation axis; i.e. act oppositely to fluids in a centrifuge. The opposing physical pictures are reminiscent of the difference between the rotational motion views of Newton and Cassini.
A hidden symmetry of collisionless sound of Bose condensates in anisotropic traps  [PDF]
Martin Fliesser,Robert Graham
Physics , 1998, DOI: 10.1103/PhysRevA.59.R27
Abstract: We derive a symmetry property for the Fourier-transform of the collisionless sound modes of Bose condensates in anisotropic traps connected with a somewhat hidden conservation law. We discuss its possible observation by dispersive light scattering.
Hydrodynamic excitations of Bose condensates in anisotropic traps  [PDF]
Martin Fliesser,András Csordás,Péter Szépfalusy,Robert Graham
Physics , 1997, DOI: 10.1103/PhysRevA.56.R2533
Abstract: The collective excitations of Bose condensates in anisotropic axially symmetric harmonic traps are investigated in the hydrodynamic and Thomas-Fermi limit. We identify an additional conserved quantity, besides the axial angular momentum and the total energy, and separate the wave equation in elliptic coordinates. The solution is reduced to the algebraic problem of diagonalizing finite dimensional matrices. The classical quasi-particle dynamics in the local density approximation for energies of the order of the chemical potential is shown to be chaotic.
Collective excitations in Bose-Einstein condensates in triaxially anisotropic parabolic traps  [PDF]
András Csordás,Robert Graham
Physics , 1998, DOI: 10.1103/PhysRevA.59.1477
Abstract: The wave equation of low-frequency density waves in Bose-Einstein condensates at vanishing temperature in arbitrarily anisotropic harmonic traps is separable in elliptic coordinates, provided the condensate can be treated in the Thomas-Fermi approximation. We present a complete solution of the mode functions, which are polynomials of finite order, and their eigenfrequencies which are characterized by three integer quantum numbers.
Generating vortex rings in Bose-Einstein condensates in the line-source approximation  [PDF]
M. Guilleumas,D. M. Jezek,R. Mayol,M. Pi,M. Barranco
Physics , 2002, DOI: 10.1103/PhysRevA.65.053609
Abstract: We present a numerical method for generating vortex rings in Bose-Einstein condensates confined in axially symmetric traps. The vortex ring is generated using the line-source approximation for the vorticity, i.e., the rotational of the superfluid velocity field is different from zero only on a circumference of given radius located on a plane perpendicular to the symmetry axis and coaxial with it. The particle density is obtained by solving a modified Gross-Pitaevskii equation that incorporates the effect of the velocity field. We discuss the appearance of density profiles, the vortex core structure and the vortex nucleation energy, i.e., the energy difference between vortical and ground-state configurations. This is used to present a qualitative description of the vortex dynamics.
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