基于里德堡原子的长波长射频场的测量

It is significantly important to measure the electromagnetic field due to it has a widely use in communication, scientific research and so on. Conventional measurement with field sensors that involve dipole antennas (which need to be calibrated first) obviously leads to a terrible measuring errors due to a huge dipole antenna for long-wavelength field. While, Rydberg atoms are well suited for rf field measurement owing to their extreme sensitivities to dc and ac electric fields, which manifest in large dc polarizabilities and microwave-transition dipole moments. Rydberg-EIT rf-modulation spectroscopy is a promising method for accomplishing an atom-based, calibration-free rf electric-field measurement. .In this proposal, spectroscopy of cesium Rydberg atoms in radio-frequency fields is studied experimentally and theoretically. An all-optical sensing approach employed by numerous groups is electromagnetically induced transparency (EIT) of atomic vapors, utilizing Rydberg levels to measure the properties of the electric field. Main contents are as following: which including four parts: 1. The investigation of Rydberg EIT dependence on experimental parameters to obtain narrow linewidth of EIT. 2. The investigation of Rydberg EIT, modulated by 0.1-1GHz Radio-Frequency fields in a room-temperature cesium cell. The RF-dressed Rydberg EIT show AC stark shift and splitting and RF sideband, which demonstrate the rich spectra structure and can be used as a calibration-free sensitive measurement of the RF field. 3. The investigation of ionization of Rydberg atom and effect on the rf field measurement. Rydberg EIT in vapor cells offers significant potential for miniaturization of the rf sensor.

电磁场强度、频率和极化方向的精密测量和计量在通讯、国防、科学研究和民用工业等方面具有重大的研究意义。传统的测量长波长射频场（<1GHz）的方法，所需探头庞大，探头灵敏度低，且金属探头对被测场产生干扰，导致测量误差较大。利用里德堡原子极化率大对外场敏感的特点可实现基于原子能级的射频电场的精密测量。.本项目拟采用全光学的电磁感应透明（EIT）作为探测手段，研究长波长射频场调制的里德堡原子射频EIT光谱，根据测量的EIT谱线特征实现射频场的精密测量。主要研究内容包括：1.研究高分辨率窄线宽的里德堡EIT光谱；2.研究频率为0.1-1GHz射频场调制的里德堡原子EIT光谱，利用边带光谱特征实现射频场的校准和测量；3.研究里德堡原子的自电离效应及其对射频场测量的影响，进一步提高测量精度，实现射频场的精密测量；在微小型样品池中实现射频场的精确测量，可探索基于里德堡原子的射频传感器件。

根据项目研究计划，我们从理论和实验上研究了长波长射频场调制里德堡能级的EIT谱线。理论上计算了阶梯型里德堡三能级系统的EIT谱线，射频场耦合里德堡系统的EIT-AT光谱，以及建立了射频场调制里德堡能级的Floquet理论模型，获得了射频 EIT 光谱与射频场强度、频率和极化方向的依赖关系，并提出了区分EIT和AT效应的标准。实验上建立了测量射频场的实验装置，通过优化实验参数获得了窄线宽的里德堡EIT光谱，并利用全光学EIT的探测方法，研究了射频长缀饰的里德堡能级，实现了射频场的精确测量，包括强度，频率和极化方向，最小测量强度小于1uV/cm，频率测量分辨率低于1Hz，精度小于0.1%。并且将上述的研究扩展到全频段射频场测量，扩展了基于里德堡原子的电场的测量带宽，该研究成果在射频电场的测量和无线通讯等方面具有重要的应用价值。超额完成了项目预期的研究内容，达到了预期的研究目标。.主要研究成果发表论文13篇，其中《Phys. Rev. A》1 篇，《New J. Phys.》2 篇, 《Opt. Express》1篇，《Appl. Sci.》3 篇，《Chin. Phys. B》3篇，以及其他期刊论文3 篇。授权发明专利2项。在项目完成中毕业博士3名，硕博连读3名。