Fragmentation of a spin-1 mixture in a magnetic field.

We study ground-state quantum fragmentation in a mixture of a polar condensate and a ferromagnetic condensate when subjected to an external magnetic field. We pay more attention to the polar condensate, due to the fact that fragmentation of a polar condensate, which typically occurs only in a very weak magnetic field, can occur in a mixture at higher magnetic fields, where both atom numbers and number fluctuations will remain of a macroscopic magnitude, of the order of N. The role of the ferromagnetic condensate is to provide a uniform and stable background which can delay the rapid shrinkage of the zero-component population and make it possible to capture "superfragmentation." Our method has potential applications in measurement of the interspecies spin-coupling interaction by adjusting the magnetic field. [ABSTRACT FROM AUTHOR]