Phase diagram, stability and magnetic properties of nonlinear excitations in spinor Bose–Einstein condensates

Abstract

The static properties, i.e., existence and stability, as well as the quench-induced dynamics of nonlinear excitations of the vortex-bright type appearing in two-dimensional harmonically confined spin-1 Bose-Einstein condensates are investigated. Linearly stable vortex-bright-vortex and bright-vortex-bright solutions arise in both antiferromagnetic and ferromagnetic spinor gases upon quadratic Zeeman energy shift variations. The precessional motion of such coherent structures is subsequently monitored dynamically. Deformations of the above configurations across the relevant transitions are exposed and discussed in detail. It is further found that stationary states involving highly quantized vortices can be realized in both settings. Spatial elongations, precessional motion and spiraling of the nonlinear excitations when exposed to finite temperatures and upon crossing the distinct phase boundaries, via quenching of the quadratic Zeeman coefficient, are unveiled. Spinmixing processes triggered by the quench lead, among others, to changes in the waveform of the ensuing configurations. Our findings reveal an interplay between pattern formation and spin-mixing processes being accessible in contemporary cold atom experiments.

Spin-current instability at a magnetic domain wall in a ferromagnetic superfluid: A generation mechanism of eccentric fractional skyrmions

“…The bulk ordered state is suppressed in the core of the DW, in which the macroscopic wave functions vary continuously between the two states. The core of a topological defect in spin-1 BECs has been revealed to exhibit complicated states [32,[39][40][41][42][43][44][45][46][47][48][49]. Similarly, there are different possibilities for the local states at the wall in our system.…”

On-demand generation of dark soliton trains in Bose-Einstein condensates

“…An immediate extension of this work points towards richer systems, e.g., spinor BECs [73][74][75]. These systems are already experimentally realizable [76][77][78], and several works have already exposed the existence of stable solitonic structures both experimentally [32] and theoretically [70,[79][80][81][82]].…”

Existence, Stability and Dynamics of Monopole and Alice Ring Solutions in Anti-Ferromagnetic Spinor Condensates

“…Following Refs. [4,46,47], we consider, in particular, a 23 Na condensate with a a = (a 2 −a 0 )/3 ≈ 2a B and a s = (2a 2 +a 0 )/3 ≈ 50a B in our simulations where a B = 0.0529 nm is the Bohr radius, thus giving c 2 /c 0 ≈ 0.04. For instance, for trapping frequencies Ω = 2π × 10 Hz and and N ≈ 4 × 10 6 , we get c 0 = 2 × 10 4 .…”

“…A key feature of spinor condensates is the presence of both spin-independent and spin-dependent interactions [8,9]. Depending on the sign of the latter, the gases can be antiferromagnetic, as in the case of 23 Na [3,4] or ferromagnetic (weakly or strongly, respectively) for 87 Rb [6,7] and 7 Li [12,13]. The phase diagram of the potential ground states (depending on the spin-dependent interactions and the role of external magnetic fields through the so-called quadratic Zeeman effect) has been extensively studied, e.g., in Ref.…”

“…Beyond such ground states, part of the wealth of the phenomenology enabled by the 3-component F = 1 and the 5-component F = 2 BECs concerns the possibility of solitonic (both topological and non-topological) excitations in them [11]. Indeed, at the one-dimensional (1D) level, both magnetic and non-magnetic structures have been theoretically proposed and experimentally observed [14][15][16][17][18][19][20][21][22] whence the phase diagram [23], as well as multi-soliton collisions [24] of some of these structures have been theoretically explored and experimentally quantified. The presence of the spin degree of freedom has also enabled the observation of spin domains [25,26] and spin textures [27,28].…”