Quantum Fluctuation And Spin Squeezing Of F=1 Spinor Bose Condensates

Spin squeezed states is a special entangled state that could improve the measurement accuracy, and received great attention. The correlation between particles is the key to realize the spin squeezing. This correlation can be accomplished by the nonlinear interaction between particles. With the MIT Ketterle group successfully obtained23 Na condensate in optical dipole trap, the studies of spinor Bose-Einstein have obtained fast development. The collision interaction occurring in BEC atoms makes atomic field contains nonlinear effect.This proves a new way to prepare non-classical states. In this paper, we study the effect of uniform magnetic field on ground-state population distribution and spin squeezing of F ?1spinor Bose condensates.This paper makes a study of the spinor BEC mixture that is formed by ferromagnetic atoms and anti-ferromagnetic atoms. When particle collide with another in the absence of an external magnetic field, because inter-species bosonic atoms are not limited to the Bose symmetry,there are three kind of total spin collision orbit,that is to say f=0,1,2. First of all, we deduce Hamiltonian of spin 1+1 mixture by DIA approximation. And on this basis we study populationdistribution of the ground state of spinor BEC mixture that is formed by ferromagnetic atoms and anti-ferromagnetic atoms and find a special state –super-fragmented state. We could arrive at spin exchange interaction of Heterogeneous atoms by this state. Second, we study the influence of external magnetic field on spin squeezing when parameters12 c ? take different values.