Internal structure and stability of vortices in a dipolar spinor Bose-Einstein condensate

Abstract

We demonstrate how dipolar interactions can have pronounced effects on the structure of vortices in atomic spinor Bose-Einstein condensates and illustrate generic physical principles that apply across dipolar spinor systems. We then find and analyze the cores of singular vortices with non-Abelian charges in the point-group symmetry of a spin-3 52Cr condensate. Using a simpler model system, we analyze the underlying dipolar physics and show how a characteristic length scale arising from the magnetic dipolar coupling interacts with the hierarchy of healing lengths of the s-wave scattering and leads to simple criteria for the core structure: When the interactions both energetically favor the ground-state spin condition, such as in the spin-1 ferromagnetic phase, the size of singular vortices is restricted to the shorter spin-dependent healing length (s-wave or dipolar). Conversely, when the interactions compete (e.g., in the spin-1 polar phase), we find that the core of a singular vortex is enlarged by increasing dipolar coupling. We further demonstrate how the spin alignment arising from the interaction anisotropy is manifest in the appearance of a ground-state spin-vortex line that is oriented perpendicularly to the condensate axis of rotation, as well as in potentially observable internal core spin textures. We also explain how it leads to an interaction-dependent angular momentum in nonsingular vortices as a result of competition with rotation-induced spin ordering. When the anisotropy is modified by a strong magnetic field, we show how it gives rise to a symmetry-breaking deformation of a vortex core into a spin-domain wall

Planar ringlike vortices

“…The work is further motivated by the current interest in vortices in condensed matter, and here we emphasize some issues, as the ones described in Refs. [53][54][55][56][57], and in references therein. For instance, in [53][54][55], the authors deal with vortices in dipolar Bose-Einstein condensates, in which the interaction between atoms are of the dipole-dipole type, leading to the presence of vortices that behave differently, acquiring nontrivial structures.…”

Controlled creation and decay of singly-quantized vortices in a polar magnetic phase

“…ortices in superfluids with internal degrees of freedom, such as those existing within spinor Bose-Einstein condensates (BECs) 1,2 and superfluid liquid He-3 3,4 , exhibit a much richer phenomenology than do simple line vortices in scalar superfluids. Notable examples abound, including vortices with fractional charges [5][6][7][8][9][10][11] , vortices with like charges that sum to zero 12 , vortices with charges that do not commute [13][14][15][16][17][18][19] , and nonsingular textures with angular momentum [20][21][22][23][24][25] . These features, among others, hint at their highly counter-intuitive dynamics.…”

Topological defects in rotating spin-orbit-coupled dipolar spin-1 Bose-Einstein condensates

“…On the other hand, quantum gases with magnetic dipole-dipole interaction (DDI), especially the BECs with DDI, have also drawn much attention both experimentally [35][36][37][38] and theoretically [39][40][41][42][43][44][45][46][47][48] in recent years. Relevant studies on spinor BECs with DDI have shown that the interplay between the short-range spin-exchange interaction and the long-range anisotropic DDI can lead to rich topological defects, spin textures and spin dynamics [39,40].…”