三能级原子-场系统中原子的偶极平方压缩

Atomic dipole amplitude-squared squeezing in the coupling system of a three-level atom with radiation field

研究了三能级原子与单模辐射真空场相互作用中原子的偶极平方压缩效应 .运用数值计算方法讨论了辐射场与原子的 2种耦合常数的相对大小以及原子的初始相干性对原子偶极平方压缩的影响 .研究结果表明 :若初始原子处于基态或最高激发态 ,则相互作用系统在演化过程中不会出现原子的偶极平方压缩效应 ;当初始原子处于基态与最高激发态的相干叠加态时 ,系统在演化过程中可出现原子偶极平方压缩效应 ;原子偶极平方压缩的深度由反映初始原子相干性的位相因子决定 ;在其他条件一定时 ,若初始原子处于最高激发态的几率为 1 4而处于基态的几率为 3 4,则原子可呈现最佳偶极平方压缩效应 ;当辐射场与原子的 2种跃迁耦合常数均不为 0时 ,压缩量呈周期性变化 ;压缩量变化的周期由 2种跃迁耦合常数的相对大小决定 .

This paper studied the atomic dipole amplitude squared squeezing in the system of a three level atom interacting with a single mode radiation vacuum field. Numerical method is adopted to discuss the influence of the relative value of atom field coupling constants and the atomic initial coherence on the squeezing effect. It is found that no squeezing is produced in the process of interaction if the atom is initially most excited or in its ground state. However, if the atom is initially in a coherent superposition state of the ground state and the most excited state, there will be dipole amplitude squared squeezing effect in the process of interaction; the squeezing degree depends on the phase factor relating to atomic initial coherence; when other conditions are fixed, the atom will produced optimum squeezing effect if the probability of atom initially in the most excited state is 1/4 and the probability of it initially in the ground state is 3/4. If none of the atom field coupling constants are zero, the quantities of squeezing vary periodically; the change period of the quantities of squeezing depends on the relative value of two atom field coupling constants.