Stripes and honeycomb lattice of quantized vortices in rotating two-component Bose-Einstein condensates

Abstract

We study numerically the structure of a vortex lattice in two-component Bose-Einstein condensates with equal atomic masses and equal intra-and inter-component coupling strengths. The numerical simulations of the Gross-Pitaevskii equation show that the quantized vortices form uncertain lattice configurations accompanying the vortex stripes, honeycomb lattices, and their complexes. This is a result of the degeneracy of the system for the SU(2) symmetric operation, which makes a continuous transformation between the above structures. In terms of the pseudospin representation, the complex lattice structures are identified to a hexagonal lattice of doubly-winding half-skyrmions.

Phase-separated symmetry-breaking vortex-lattice in a binary Bose-Einstein condensate

“…In this paper, we will be interested in robust spontaneoussymmetry breaking phase separated vortex lattices without overlap between component densities, which is of (g)-(h). This type of density distribution is called vortex sheet structure which has been found before in binary BECs [15,24]. This case is not of interest of the present study.…”

“…There has also been study of vortex-lattice formation in a BEC along the weak-coupling to unitarity crossover [12] and in a rotating box trap [13]. The study of vortex lattices in a binary or a multi-component spinor BEC is interesting because the interplay between intra-species and interspecies interactions may lead to the formation of square [8,14], stripe and honeycomb [15] vortex lattice, other than the standard Abrikosov triangular lattice [7]. In addition, there could be the formation of coreless vortices [16], vortices of fractional charge [17,18], and phaseseparated vortex lattices in multi-component non-spinor [19] spinor [11] and dipolar [14] BECs.…”

Symmetry-breaking vortex-lattice of a binary superfluid in a rotating bucket

“…We consider a large g 12 , as for a large g 12 , the phase separation is robust, leading to a ground state with phase-separated vortex lattice. For g 12 g 1 = g 2 , there is a phase separation, and the ground state of a harmonically trapped binary BEC has a phaseseparated sheet structure [18,23]. In Figs.…”

“…In Figs. 8(a)-(b) we display the numerically obtained number of vortices and the Ω-dependent energy in the rotating frame versus Ω, respectively, for a rotating quasi-2D binary BEC in a square bucket and compare these with the estimate of Feynman for the number of vortices (18) and of Fetter for energy (21), respectively. Actually, the estimate of Feynman for the number of vortices is valid in a large system.…”

“…The study of vortex lattices in a binary or a multicomponent spinor BEC is interesting because it may lead to the formation of square [14,16,17], stripe [14] and honeycomb [18] vortex lattices, other than the standard Abrikosov triangular lattice [3], in addition to coreless vortices [19], vortices of fractional charge [20], and phase-separated vortex lattices in multi-component nonspinor [21] and dipolar [17] BECs. The difficulty of experimental study of overlapping vortices in different components of a multi-component BEC is monumental and despite great interest [22,23], there are only a few experimental studies [16,24] on vortex lattices in a rotating binary BEC.…”