Search for dark matter axions with Rydberg atoms

在宇宙中寻找暗物质粒子是与粒子物理学和天体物理学相关的最重要问题之一。轴子被用来解决QCD理论中所谓的“强CP问题”，是暗物质粒子的主要候选者。我们提出用里德伯原子在强磁场渗透的谐振腔中寻找暗物质轴子。在该方案中，通过Primakoff过程的轴子转换产生的微波光子被以束态通过腔体的里德伯原子探测到。这个方案现在被认为是搜索轴子最有效的方法。考虑谐振腔的有限温度和有限阻尼时间，对谐振腔中轴子与里德伯原子和光子的相互作用进行了量子理论处理。在理论分析的基础上，我们开发了一个寻找轴子的实验系统，用稀释制冷机将空腔冷却到10mK，用三步激光激发产生的里德伯原子检测轴子。这台仪器经过了成功的测试，现在准备开始寻找质量在10mueV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.