Bose-Einstein condensation of spinor S=1 bosons

Qiang Gu

It was reported that Bose-Einstein condensation induces a spontaneous magnetization in spinor bosons. This phenomenon is called Bose-Einstein ferromagnetism (BEF). We propose a phenomenological model consistent with the prediction of BEF and show that BEF might be attributed to the intrinsic magnetic moment of particles. Taking BEF into account, the phase diagram of an optically trapped spinor condensate is reexamined.

Fabrizio Tafuri, C. A. Perroni, G. De Filippis

Bao Cheng-guang, Zhibing Li

The analytical expressions of the fractional parentage coefficients for the total spin states of a spinor $N$-boson system have been derived. Thereby an $S$-conserved theory for the spinor Bose-Einstein condensation has been proposed. A set of equations has been established to describe the first excited band of the condensates. Numerical solution for $^{23}\mathrm{Na}$ has been given as an example.

Yuki Kawaguchi, Masahito Ueda

Александр Сергеевич Пелетминский, S. V. Peletminsky, Yu. V. Slyusarenko

Nille N. Klausen, John L. Bohn, Chris H. Greene

We perform detailed close-coupling calculations for the rubidium isotopes ${}^{85}\mathrm{Rb}$ and ${}^{87}\mathrm{Rb}$ to ascertain the nature of their spinor Bose-Einstein condensates. These calculations predict that the spinor condensate for the spin-1 boson ${}^{87}\mathrm{Rb}$ has a ferromagnetic nature. The spinor condensates for the spin-2 bosons ${}^{85}\mathrm{Rb}$ and ${}^{87}\mathrm{Rb},$ however, are both predicted to be polar. The nature of a spin-1 condensate hinges critically on the sign of the difference between the s-wave scattering lengths for total spins 0 and 2 while the nature of a spin-2 condensate depends on the values of the differences between s-wave scattering lengths for the total spins 0, 2, and 4. These scattering lengths were extracted previously and found to have overlapping uncertainties for all three cases, thus leaving the nature of the spinor condensates ambiguous. The present study exploits a refined uncertainty analysis of the scattering lengths based on recently improved result from experimental work by Roberts et al., which permits us to extract an unambiguous result for the nature of the ground state spinor condensates.