Energetically stable singular vortex cores in an atomic spin-1 Bose-Einstein condensate

Abstract

We analyze the structure and stability of singular singly quantized vortices in a rotating spin-1 Bose-Einstein condensate. We show that the singular vortex can be energetically stable in both the ferromagnetic and polar phases despite the existence of a lower-energy nonsingular coreless vortex in the ferromagnetic phase. The spin-1 system exhibits an energetic hierarchy of length scales resulting from different interaction strengths, and we find that the vortex cores deform to a larger size determined by the characteristic length scale of the spin-dependent interaction. We show that in the ferromagnetic phase the resulting stable core structure, despite apparent complexity, can be identified as a single polar core with an axially symmetric density profile which is nonvanishing everywhere. In the polar phase, the energetically favored core deformation leads to a splitting of a singly quantized vortex into a pair of half-quantum vortices that preserves the topology of the vortex outside the extended core region, but breaks the axial symmetry of the core. The resulting half-quantum vortices exhibit nonvanishing ferromagnetic cores.

Topological interface physics of defects and textures in spinor Bose-Einstein condensates

“…In a rotating FM spin-1 BEC, the coreless vortex has the lower energy and the lower nucleation barrier, and consequently the ground state is made up of nonsingular coreless vortices for sufficiently rapid rotation [53,54,57,58,61]. However, it is also possible to form a singly quantized, singular vortex [51,52], which despite not being the lowest-energy state at any frequency of rotation can nevertheless be energetically stable as a local energy minimum [63].…”

“…(a) A singly quantized vortex in the polar phase connecting to a doubly quantized vortex on the FM side may be cut in half at the interface and the resulting vortices in the two regions may be moved apart if an additional dark soliton plane is introduced in ζ 0 . (b) A singly quantized polar vortex can split into two half-quantum vortices when its energy relaxes [63]. A repulsive force between the half-quantum vortices makes the splitting energetically favorable.…”

“…5(b), and the deformation is understood in terms of the characteristic length scales set by the atom-atom interactions. In the purely polar or FM condensate, the core-deformed, singly quantized vortices are energetically stable [63]. investigated, the configuration in Fig.…”

“…Perhaps the simplest of such structures where the multicomponent nature of BECs plays an important role are one-dimensional (1D) vector solitons [36][37][38][39][40][41][42][43], typically consisting of stable combinations of dark and bright solitons in different condensate components. Higher-dimensional defects and textures include vortex sheets [44] and 3D particlelike solitons [20][21][22][45][46][47] in two-component (pseudospin-1/2) condensates, as well as a rich phenomenology of defects and textures in spin-1 [23,24,26,[48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63], spin-2 [64][65][66], and spin-3 [30,67] BECs. Interface physics has been studied in two-component BEC systems, for example, in the context of vortex bifurcation at energetically established interfaces in the phase-separation regime [68,69] and interface collisions [19].…”

Bell‐Polynomial Approach and Integrability for the Coupled Gross–Pitaevskii Equations in Bose–Einstein Condensates

“…Work in connection with the dynamics of nonlinear matter‐wave solitons in the BECs has been done, such as the spontaneous symmetry breaking , symbiotic solitons , vortex dynamics , interference patterns , domain walls , and four‐wave mixing . Solitons in the BECs have been studied with time‐varying parameters, including the time‐dependent atomic wave scattering lengths which can be influenced by the Feshbach resonance, time‐varying gain or loss from the thermal cloud, and effects of variables diffraction .…”