Quantum Effects of Many Atoms in Spinor Bose--Einstein Condensates

We have studied the evolutions of the population transfer, tunnelling current and antibunching effects between spin-(+1) and spin-(-1) in the case of the strong laser pulses. It is found that the population transfer and tunnelling current exhibit periodical oscillation. For the same Rabi frequency, the larger the atom number, the longer the oscillation period is. For the spin-(-1) component, when the atomic numbers are N=4 and 10, the antibunching effect can appear. For different atomic numbers, the appearing regions are very different. For spin component +1, the antibunching effect can always appear for different atomic numbers.