We demonstrate a method of micromotion minimization of a trapped ion in a linear Paul trap based on the precision measurement of the ion trapping position displacement due to a stray electric field in the radial plane by ion fluorescence imaging. The amount of displacement in the radial plane is proportional to the strength of a stray electric field. Therefore, we evaluated the micromotion compensation condition by measuring the ion displacements from the ion equilibrium position using two different radial trap frequencies with various combinations of the compensation voltage. The residual electric field uncertainty of this technique reached a few volts per meter. This compensation technique does not depend on the orientation of the incident cooling laser or the detuning and imaging direction. Therefore, this method is suitable for a planar ion trap, a stylus ion trap, which limits the propagation angle of lasers, or miniaturized ion trap systems for sensing and metrological applications.
High-energy-resolution measurement of ultracold atom-ion collisional cross section
给定过程的截面从根本上量化了该给定过程发生的概率。在低能量的量子区域中，由于量子效应，截面可以随着碰撞能量强烈地变化。在这里，我们报告了一种方法，直接测量原子-离子碰撞截面的能量范围为0.2-12 mK $\cdot$ k $_B$，通过穿梭超冷原子捕获在一个光学晶格通过射频捕获离子。在该方法中，每次实验的原子-离子碰撞的平均数低于1，使得能量分辨率不受宽（幂律）稳态原子-离子能量分布的限制。在这里，我们估计能量分辨率低于200 $μ$ K $\cdot$ k $_B$，受到离子的过量微动补偿中的漂移的限制，并且可以降低到10的$μ$ K $\cdot$ k $_B$制度。这种分辨率比以前测量冷原子-离子碰撞截面能量依赖性的实验好一个数量级。我们用我们的方法测量了非绝热电子激发交换（EHT）和自旋轨道变化（SOC）过程的非弹性碰撞截面的能量依赖性。我们发现，在所测量的能量范围内，电子态和SOC截面与经典的朗之万截面在统计上一致。这种方法允许测量各种非弹性过程的截面，并开辟了可能性，以寻找原子离子的量子签名，如形状共振。
Cold-Atom Buoy: A Differential Magnetic Sensing Technique in Cold Quadrupole Traps
HUN-REN Wigner Research Centre for Physics（匈牙利研究网络温格物理研究中心）；Department of Physics of Complex Systems, ELTE Eötvös Loránd University（厄特沃什·罗兰大学复杂系统物理系）；Center for Quantum Science, Physikalisches Institut, Eberhard Karls Universität Tübingen（蒂宾根大学物理研究所量子科学中心）；Department of Theoretical Physics, Institute of Physics, Budapest University of Technology and Economics（布达佩斯技术与经济大学物理研究所理论物理系）
