Dynamics of a massive superfluid vortex in rk confining potentials

Abstract

We study the motion of a superfluid vortex in condensates having different background density profiles, ranging from parabolic to uniform. The resulting effective point-vortex model for a generic power-law potential ∝r k can be experimentally realized with recent advances in optical-trapping techniques. Our analysis encompasses both empty-core and filled-core vortices. In the latter case, the vortex acquires a mass due to the presence of distinguishable atoms located in its core. The axisymmetry allows us to reduce the coupled dynamical equations of motion to a single radial equation with an effective potential V eff . In many cases, V eff has a single minimum, where the vortex precesses uniformly. The dynamics of the vortex and the localized massive core arises from the dependence of the energy on the radial position of the vortex and from the r k trap potential. We find that a positive vortex with small mass orbits in the positive direction, but the sense of precession can reverse as the core mass increases. Early experiments and theoretical studies on two-component vortices found some qualitatively similar behavior.

Making ghost vortices visible in two-component Bose-Einstein condensates

“…The resulting "massive vortices" represent composite topological excitations of the mixture [38,53,54], and are stabilized by the assumed immiscibility g ab > √ g aa g bb of the two components (if this condition is violated, a non-negligible mass can be still present in the vortex core, but it is not tightly localized therein [55,56]). While considerable attention has been paid to their dynamics [38,[40][41][42], important properties of the filling component ψ b are still unaddressed.…”

“…A particularly convenient analytical tool to estimate the dynamics of massive quantum vortices, as well as the properties of rotating N -gons of massive vortices is represented by the massive point vortex model [38,[40][41][42], which generalizes previous point-vortex models [45] where the possible presence of core mass was neglected. In the framework of a time-dependent variational approximation, in fact, superfluid Vortex Dynamics and Newtonian inertial Physics can be treated on equal footing and the resulting effective point-like Lagrangian where…”

“…was shown to well capture the trajectories of interacting massive vortices [38,[40][41][42], bypassing the need of solving the actual GP equations ( 1) and (2). The meaning of model parameters in Lagrangian (3) is the following:…”

“…r j ×ẑ can be regarded as an effective vector potential [40,41]. Similarly, the Hamiltonian ( 8) is written in terms of the canonical variables…”

“…In this work, we focus on a class of systems where ghost vortices not only are present but play a crucial role in the overall dynamics: two-component BECs in the immiscible regime, where one component hosts quantum vortices and the other component fills vortex cores. The dynamical properties of these "massive vortices" [38][39][40][41][42] are determined by the interplay of superfluid Vortex Dynamics [43][44][45][46] and Newtonian (inertial) physics, and disclose intriguing phenomena such as the presence of cyclotronlike orbits [40], precession reversal [41], and two-vortex collisions [42].…”