Search for dark matter axions with Rydberg atoms

寻找宇宙中的暗物质粒子是粒子物理和天体物理中最重要的问题之一。用来解决QCD理论中所谓的“强CP问题”的轴子是暗物质粒子的主要候选者。我们提出在强磁场穿透的共振腔中寻找具有里德堡原子的暗物质轴子。在这个方案中，通过Primakoff过程轴子转换产生的微波光子被里德堡原子以光束状态通过腔来探测。这个方案被认为是目前寻找轴子的最有效的方法。我们发展了一种量子理论处理轴子与里德堡原子和共振腔中的光子的相互作用，考虑了腔的有限温度和有限的衰减时间。在理论分析之后，我们发展了一套实验系统来寻找轴子，其中空腔用稀释制冷机冷却到10mK，轴子是用三步激光激发产生的里德堡原子探测的。该装置测试成功，现在准备开始寻找质量在10-V左右的轴子。

Search for dark matter particles in the Universe is one of the most important issue related to particle physics and astrophysics. Axions, invoked to solve the so called "strong CP problem" in the QCD theory, is a leading candidate for the dark matter particles.We have proposed to search for dark matter axions with Rydberg atoms in resonant cavities permeated by strong magnetic field. In this scheme, microwave photons produced by conversion of axions via the Primakoff process are detected by Rydberg atoms passed through a cavity in a state of beam. This scheme is considered now to be the most efficient way to search for axions.We developed a quantum theoretical treatment of the interactions of axions with Rydberg atoms and photons in resonant cavities by taking into account the finite temperature and the finite damping time of the cavities. Following the theoretical analyzes, we developed an experimental system to search for axions where the cavities are cooled down to 10mK with a dilution refrigerator and the axions are detected with Rydberg atoms produced by three-step laser excitations. The apparatus was successfully tested and now ready to start the search for axions with mass around 10mueV.