Spinor Bose Condensates in Optical Traps

TLDR

In optical traps, spin‑1 bosons such as $^{23}$Na, $^{39}$K, and $^{87}$Rb can adopt either ferromagnetic or polar ground states, with distinct collective modes and vortex stability, including coreless Skyrmion‑like vortices in the ferromagnetic phase. Current estimates of scattering lengths indicate that $^{23}$Na condenses in a polar state while $^{87}$Rb condenses in a ferromagnetic state.

Abstract

In an optical trap, the ground state of spin-1 Bosons such as $^{23}$Na, $^{39}$K, and $^{87}$Rb can be either a ferromagnetic or a "polar" state, depending on the scattering lengths in different angular momentum channel. The collective modes of these states have very different spin character and spatial distributions. While ordinary vortices are stable in the polar state, only those with unit circulation are stable in the ferromagnetic state. The ferromagnetic state also has coreless (or Skyrmion) vortices like those of superfluid $^{3}$He-A. Current estimates of scattering lengths suggest that the ground states of $^{23}$Na and $^{87}$Rb condensate are a polar state and a ferromagnetic state respectively.