Bogoliubov excitations of two-component BEC supported by different vortex configurations

Sungjong Woo, Seok Jin Choi, Leslie O. Baksmaty +1 more

In a rotating two-component Bose-Einstein condensate (BEC), the traditional triangular vortex lattice can be replaced by a rectangular vortex lattice or even a structure characterized in terms of vortex sheets, depending on the interspecies interactions. We study the dynamics of this system by analyzing the Bogoliubov excitation spectrum. Excitations familiar to BEC vortex systems are found such as Tkachenko modes, hydrodynamic modes, and surface waves, however, the complex two-component morphology also gives rise to phenomena including shear flow between vortex sheets.

Nicola K. Wilkin

Tomoya Isoshima, Kazushige Machida, Tetsuo Ohmi

Quantum vortices in the multi-component Bose-Einstein condensation (BEC) are investigated theoretically. It is found that three kinds of the vortex configurations are possible and their physical properties are discussed in details, including the density distribution and the spin texture. By using the Bogoliubov theory extended to the three component BEC, the collective modes for these vortices are evaluated. The local vortex stability for these vortices are examined in light of the existence of the negative eigenvalue, yielding a narrow magnetization window for the local intrinsic stable region where the multi-components work together to stabilize a vortex in a self-organized way.

P. G. Kevrekidis

Qing-Li Zhu

Qing-Li Zhu, Lihua Pan, Jin An

We study the dynamics of a quasi-two-dimensional (2D) spin-orbit-coupled ferromagnetic Bose-Einstein condensate (BEC) under a linear Zeeman magnetic field disturbed by a moving obstacle. The Bogoliubov excitation spectrums and corresponding critical excitations in different situations are analyzed. The structure of the coreless vortex or antivortex generated by the moving obstacle has been investigated. When the Zeeman field is parallel to the 2D system plane, the vortex cores for the three components of a (an) vortex (antivortex) could be arranged into a line which is vertical to the Zeeman field, and their order would be reversed as the spin-orbit coupling increases. When the Zeeman field is perpendicular to the plane, a skyrmionlike vortex ground state could be induced via spin-orbit interaction even by a static obstacle and thus becomes unique in contrast with the scalar BECs or spinor BECs without spin-orbit coupling. This topological structure is also found to be dynamically stable if the obstacle is moving at a relatively small velocity.