It is shown that the metastate exist only in some parameter region.The decay of the metastable-state via quantum tunneling is studied and the life time is found analytically by instanton method.

• 通过介观自旋算符建立了体系的精确量子相位模型，利用对量子自旋的势场描述给出了在两阱中振荡的原子之间相位差为时，即亚稳态时所要满足的物理条件，并用瞬子方法计算了该亚稳态存在的寿命。