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原子极化率反映其对外场的响应特性, 动态极化率等于零的外场波长称为零极化或幻零(tune-out)波长. 里德伯原子的tune-out波长计算较为困难, 本文设计室温气室里德伯原子测量装置, 基于调幅电磁感应透明(amplitude modulation electromagnetically induced transparency, AM-EIT)光谱技术实现tune-out波长测量. 实验采用双光子级联激发制备铯原子里德伯态, 利用阶梯型电磁感应透明(electromagnetically induced transparency, EIT)光谱实现里德伯原子量子态检测; 通过微波频率连续扫描测量里德伯原子AM-EIT信号; 在tune-out波长处, 邻近耦合能级对目标里德伯态的动态极化为零, 原子动态Stark效应相消, AM-EIT信号极弱. 我们建立简化三能级模型计算tune-out波长, 理论与实验结果基本符合.The atomic polarizability represents the response characteristics of atoms to externally applied electro-magnetic fields. The wavelength (or frequency) at which the dynamic polarizability of an atom is equal to zero is referred to as the tune-out wavelength (or frequency). Spectroscopy technology based on the tune-out effect has potential applications in quantum precision measurement, quantum computation and quantum communication. Related research topics include the measurement of fundamental physical constants and strong interactions. The tune-out wavelengths of atoms in low-lying states primarily fall within the optical band, where the theoretical calculations and experimental measurements have significant progress. However, for Rydberg atoms in highly excited states, theoretical calculations are challenging due to their high density of atomic states. The difficulty of experimental measurement arises from small splitting of adjacent atomic energy levels. In this paper, we demonstrate the tune-out wavelengths measurement for Rydberg atoms in a cesium vapor cell at room temperature. We utilize a two-photon cascade excitation to prepare Rydberg states and employ amplitude-modulation electromagnetically-induced transparency (AM-EIT) spectroscopy to measure the tune-out wavelength. By continuously scanning the microwave frequencies, we obtain AM-EIT signals of Rydberg atoms. At near-resonant microwave transition wavelengths, strong AM-EIT signals are observed due to microwave-atom coupling. Conversely, at tune-out wavelengths, the dynamically polarization-induced destructive interference in neighboring energy states occurs which leads to the weak AM-EIT signals. The AM-EIT provides a spectral resolution of about 10 MHz. We have developed a simplified three-level model to calculate the tune-out wavelength. The results of our theoretical calculations are consistent with the experimental findings within a range of ±90 MHz.
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Keywords:
- Rydberg atom /
- cesium atoms /
- electromagnetically induced transparency spectrum /
- tune-out wavelength








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