利用梯度电场测量里德堡钠原子偶极矩的实验研究

原子的偶极矩与其主量子数n平方成正比，对应于n=50的里德堡原子其诱导偶极矩高达6000个德拜，远大于其基态的偶极矩（<1个德拜），人们利用这一性质实现了里德堡原子间的强偶极相互作用。但是，原子处于不同量子态时的偶极矩大小并不相同，并且还与原子量子亏损和所处外场大小相关。如果将里德堡原子处于外梯度电场中，原子将受到较强的作用力而改变运动。原子在梯度电场中所受的力与原子的偶极矩和电场梯度大小成正比。基于这个原理，本项目以现有的里德堡原子飞行时间谱仪为平台，将带电的微米尺寸的金属丝置于中空的法拉第圆筒形成圆柱形的梯度电场，然后将经过氦气超声束冷却了的钠原子束导入金属丝附近，利用原子成像技术探测里德堡原子在梯度电场中的偏转，由于所构造的梯度电场具有严格的数学解析形式，从而可以定量测量里德堡原子的平均偶极矩，这对原子的内部量子态信息了解和其偶极应用具有重要意义。

The electric dipole moment of atom is proportional to its principal quantum number n. For example, the dipole moment value of atom of n=50 is much larger than that in the ground state (<1 Debye), based on which people have realized the strong dipole-dipole interaction between atoms. However, the dipole moment of atom has different values in different quantum states, even in the same quantum states but in different external electric fields, which leads to difficulty in determining its exact value. If Rydberg atom is placed in a gradient electric field, it will feel a strong force and change its kinetic motion, based on which we can measure the dipole moment value. In this application, we will form a gradient electric field by placing a metal wire in the center of a Faraday Cylinder at the end of a time-of-flight spectrometer and then guide the sodium atom cooled by supersonic helium beam close to the wire. The atom deflection from the wire can be recorded by the imaging system and reversely we can estimate the net dipole moment of Rydberg atom since the gradient field has a strict mathematical expression. This research is meaningful in obtaining the quantum state information of atom and its application in dipole-dipole interactions.