Spin-textures of the Bose-Einstein condensates with three kinds of spin-1 atoms

TL;DR

This paper investigates the spin-textures of ground states in Bose-Einstein condensates with three spin-1 atom species, classifying textures based on spin orientations and magnitudes, and identifying transition points analytically.

Contribution

It provides a combined quantum and classical analysis of spin-textures, classifies possible configurations, and derives analytical formulas for transition points.

Findings

Two main types of spin-textures identified: parallel/anti-parallel and coplanar orientations.

Four classes of spin-magnitudes configurations: all singlet-pairs, fully polarized, mixed, and fully polarized for all species.

Analytical formulas for critical values of spin-texture transitions in Type-I.

Abstract

We have performed a quantum mechanic calculation (including solving the coupled Gross-Pitaevskii equations to obtain the spatial wave functions, and diagonalizing the spin-dependent Hamiltonian in the spin-space to obtain the total spin state) together with an analytical analysis based on a classical model. Then, according to the relative orientations of the spins $S_A$, $S_B$ and $S_C$ of the three species, the spin-textures of the ground state can be classified into two types. In Type-I the three spins are either parallel or anti-parallel to each others, while in Type-II they point to different directions but remain to be coplanar. Moreover, according to the magnitudes of $S_A$, $S_B$ and $S_C$ the spin-textures can be further classified into four kinds, namely, $p$+$p$+$p$ (all atoms of each species are in singlet-pairs), one species in $f$ (fully polarized) and two species in $q$ (a mixture of polarized atoms and singlet-pairs), two in $f$ and one in $q$, and $f$+$f$+$f$. Other combinations are not allowed. The scopes of the parameters that supports a specific spin-texture have been specified. A number of spin-texture-transitions have been found. For Type-I, the critical values at which a transition takes place are given by simple analytical formulae, therefore these values can be predicted.