微波协助下电场中里德堡原子动力学控制的实验研究

外电场中里德堡原子的能级之间存在丰富的相互作用和避免交叉能级结构，是研究Landau-Zener隧穿效应（LZT）及其应用的理想量子体系。不同于基态或低激发态原子，高里德堡态原子的能级非常密集，由于量子亏损的存在，引入较弱的外电场就能使这些能级间发生耦合相互作用，形成避免交叉能级结构；控制外电场的变化快慢就可以实现这些量子态间的绝热和非绝热演化。但是，通常原子体系的避免交叉能隙仍较大，发生显著的非绝热LZT对电场控制设备的时间响应要求较高。我们提出利用微波协助的电场控制方案，即利用微波耦合两个避免交叉能级，而外电场控制量子态演化到微波耦合点及其停留时间，从而可以在较长的时间内准确定量控制LZT过程。我们拟选择金属钠原子的蓝态和红态能级，利用红态原子的共振电离特性作为探针，演示微波协助下的电场LZT动力学过程，为下一步利用LZT制备相干量子波包及其应用奠定物理基础。

Rydberg atom in external electric field has rich interactions between its energy levels and owns wealthy avoided crossing level structure, which is an ideal quantum system to study Landau Zener tunneling (LZT) and its application. Unlike the atom located in the ground state or low excited states, high Rydberg state atom has high density of energy levels. Due to its non-zero quntumn defect, an introduction of even weak electric field can make these energy levels couple each other, forming avoided level structure, and a controlled variation of electric field applied can drive the quantum state of atom to evolve along adiabatic or non-adiabatic paths. However, usually, the energy gap between the avoided levels is not small enough and an obvious non-adiabtic LZT requires the variation of the electric field to occur in a very short time, which is beyond the time response of usual electric field generator, making it difficult to control the LZT process in real time and holding back its further application. Here we propose a scheme of electric field shaping with the aid of microwave employed, where the microwave couples the adjacent avoided energy levels instead while the external electric field controls the quantum state to evolve to the microwave coupling point and the staying time at the point, then prolongs the operation time of controlling the LZT process. We will choose the metal Rydberg atom in blue state and red state as the targets, and demonstrates its controllable LZT ionizaion dynamics in electric field, where the resonant ionization of red state serves as a probe to monitor the LZT process. This work will consolidate an important physical step for further preparing coherent quantum wavepacket by LZT as well as its application.