Title: High-sensitivity molecular spectroscopy of SrOH using magneto-optical trapping Show Chinese title

Title: 使用磁光捕获的SrOH高灵敏度分子光谱学

Abstract: Polyatomic molecules are projected to be powerful tools in searches for physics beyond the Standard Model (BSM), including new CP-violating (CPV) interactions and ultralight dark matter (UDM) particles. Certain degrees of freedom present in polyatomic molecules enhance the sensitivity of these searches, as well as reject systematic errors, but necessitate extensive high-precision spectroscopy to identify pathways for optical cycling and quantum state readout. Here we show how a magneto-optical trap (MOT) can be used to locate weak optical transitions and identify rovibronic states for optical cycling and quantum control. We demonstrate this spectroscopic approach with strontium monohydroxide (SrOH), which is a candidate for both CPV and UDM searches. We identify two new repumping transitions in SrOH and implement them in a deeper optical cycle to achieve 32400(4700) trapped molecules, a 4.5-fold increase over the previous, shallower cycle. In addition, we determine the energy spacing between the $X^{2}\Sigma^{+}(200)$ and $X^{2}\Sigma^{+}(03^10)$ vibrational manifolds of SrOH, confirming the existence of numerous low-frequency rovibrational transitions that are sensitive to temporal variations of the proton-to-electron mass ratio, a predicted effect of the existence of UDM. Show Chinese abstract

Abstract: 多原子分子被预测为寻找标准模型以外的物理（BSM）的强大工具，包括新的CP破坏（CPV）相互作用和超轻暗物质（UDM）粒子。 多原子分子中存在的某些自由度增强了这些搜索的灵敏度，并能排除系统误差，但需要广泛的高精度光谱学来确定光学循环和量子态读出的路径。 在这里，我们展示如何使用磁光陷阱（MOT）来定位弱光学跃迁，并确定用于光学循环和量子控制的振转态。 我们通过锶单羟基（SrOH）证明了这种光谱方法，SrOH是CPV和UDM搜索的候选物。 我们在SrOH中发现了两条新的再泵浦跃迁，并在更深的光学循环中实现了它们，以获得32400(4700)个被捕获的分子，比之前的较浅循环增加了4.5倍。 此外，我们确定了SrOH中$X^{2}\Sigma^{+}(200)$和$X^{2}\Sigma^{+}(03^10)$振动流形之间的能量间隔，确认了大量对质子与电子质量比的时间变化敏感的低频振转跃迁的存在，这是UDM存在的一种预测效应。