Double-quantum spin vortices in SU(3) spin-orbit-coupled Bose gases

Abstract

We show that double-quantum spin vortices, which are characterized by doubly quantized circulating spin currents and unmagnetized filled cores, can exist in the ground states of SU(3) spin-orbit coupled Bose gases. It is found that the SU(3) spin-orbit coupling and spin-exchange interaction play important roles in determining the ground-state phase diagram. In the case of effective ferromagnetic spin interaction, the SU(3) spin-orbit coupling induces a three-fold degeneracy to the magnetized ground state, while in the antiferromagnetic spin interaction case, the SU(3) spin-orbit coupling breaks the ordinary phase rule of spinor Bose gases, and allows the spontaneous emergence of double-quantum spin vortices. This exotic topological defect is in stark contrast to the singly quantized spin vortices observed in existing experiments, and can be readily observed by the current magnetization-sensitive phase-contrast imaging technique.

Gauge-potential-induced rotation of spin-orbit-coupled Bose-Einstein condensates

“…This is not only different from the Abrikosov triangular lattice of superconductors [42], but also from the square or hexagonal lattice discovered in traditional multi-component superfluids [7,[61][62][63][64]. It should also be emphasized that in the coaxially annular arrays all the vortices take the same direction of circulation which different from those spontaneous vortex lattices in a irrotational SO-coupled system, where vortices and antivortices emerge in pairs [65][66][67][68][69][70].…”

SU(3) Spin–Orbit Coupled Rotating Bose–Einstein Condensate Subject to a Gradient Magnetic Field

“…To begin with, we consider a quasi-two-dimensional (Q2D) spin-1 BEC with SU(3) SOC [27], which is confined in a controllable magnetic field [36]. Under the mean-field approximation, the Hamiltonian of such a system can be written as [42][43][44]…”

“…Only few works consider the SU(3) SOC, where the spin operators are spanned by the Gell-Mann matrices, which is more effective in describing the internal couplings among three-component condensates, such as a spin-1 Bose-Einstein condensate (BEC). Recently, Han and his co-authors have considered a homogenous SU(3) SO-coupled Bose gas and obtained the double-quantum spin vortices [27]. On the base of their pioneering research work, Li and Chen have studied the SU(3) SO-coupled BEC confined in a harmonic plus quartic trap [28].…”

Flipping-shuttle oscillations of bright one- and two-dimensional solitons in spin-orbit-coupled Bose-Einstein condensates with Rabi mixing

“…The SOC being a linear effect by itself, its interplay with the intrinsic nonlinearity of the BEC, which is usually induced, in the mean-field approximation, by contact inter-atomic collisions or long-range dipole-dipole interactions, produces various localized structures, such as vortices [13][14][15][16][17], monopoles [18], skyrmions [19,20], and dark solitons [21,22]. The use of periodic potentials, induced by optical lattices, offers additional possibilities -in particular, the creation of gap solitons [23,24,57].…”

“…Two fundamental types of the SOC, well known from works on physics of semiconductors, which are represented by the Dresselhaus [9] and Rashba [8] Hamiltonians, as well as the Zeeman-splitting effect [7], may be simulated in the atomic BEC. While the initial experiments on the SOC emulation realized effectively one-dimensional (1D) settings [10,11], the implementation of the SOC in an effectively 2D geometry was reported too [12].The SOC being a linear effect by itself, its interplay with the intrinsic nonlinearity of the BEC, which is usually induced, in the mean-field approximation, by contact inter-atomic collisions or long-range dipole-dipole interactions, produces various localized structures, such as vortices [13][14][15][16][17], monopoles [18], skyrmions [19,20], and dark solitons [21,22]. The use of periodic potentials, induced by optical lattices, offers additional possibilities -in particular, the creation of gap solitons [23,24,57].The conventional repulsive sign of inter-atomic forces can be switched to attraction by means of the Feshbach resonance [26,27], which suggests possibilities for the creation of bright matter-wave solitons [28][29][30][31], in addition to the well-known dark ones [32].…”