We study a spin-1 ultracold Bose gas in the presence of both external and synthetic magnetic fields via mean-field approach corresponding to both signs of the spin-dependent interaction potential. The synthetic field is included through the hopping frequencies via Peierls coupling and the external field through the Zeeman interaction term to explore the influence of one over the other. The antiferromagnetic case shows that at low values of external field strengths, the spin singlet state is stable and the system is more likely in Mott insulating (MI) phase as the synthetic field is enhanced. But at large external fields, due to a competition between the hopping and the Zeeman interaction terms, the former tends to stabilize the MI phase compared to the superfluid (SF) phase, while the latter tries to destabilize the MI phase by suppressing the formation of singlet pairs. In the ferromagnetic case, insensitivity of the phase properties to the external magnetic field leads to stabilization of the MI phase with increasing synthetic magnetic field. Further the magnetization shows that there are distinct signatures of transverse polar and longitudinal ferro SF phases for both antiferromagnetic and ferromagnetic interactions, respectively.
Polarization-dependent phase-contrast imaging is used to resolve the spatial magnetization profile of an optically trapped ultracold gas. This probe is applied to Larmor precession of degenerate and nondegenerate spin-1 87Rb gases. Transverse magnetization of the Bose-Einstein condensate persists for the condensate lifetime, with a spatial response to magnetic field inhomogeneities consistent with a mean-field model of interactions. In comparison, the magnetization of the non-condensed gas decoheres rapidly. Rotational symmetry implies that the Larmor frequency of a spinor condensate be density independent, and thus suitable for precise magnetometry with high spatial resolution.
The thermal conductivity of a spin-polarized atomic-hydrogen gas and its accommodation coefficient on saturated superfluid
4He films have been determined experimentally using a cell comprised of coaxial cylinders. The thermal conductivity was measured for temperatures 0.3T0.4 K and for magnetic fields 4.00H7.00 T. The value of the thermal conductivity for spin-polarized hydrogen is 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$ W/K m for T=0.3 K and H=7.00 T. The measured thermal conductivity is independent of the applied magnetic field, and its magnitude and temperature dependence are in agreement with ab initio calculations for a paramagnetic Bose gas model. No evidence for anomalous transport due to thermal fluctuations in the gas magnetization has been observed. The accommodation coefficient for spin-polarized hydrogen upon saturated superfluid
4He films for 0.2T0.4 K and 3.00H7.00 T was found to be independent of the applied magnetic field and to be given by the expression
ac=(0.56\ifmmode\pm\else\textpm\fi{}0.06)T. This value is in agreement with previous measurements of the accommodation and sticking coefficients.