The softness of elastic atomic collisions, defined as the average number of collisions each atom undergoes until its energy decorrelates significantly, can have a considerable effect on the decay dynamics of atomic coherence. In this paper we combine two spectroscopic methods to measure these dynamics and obtain the collisional softness of ultra-cold atoms in an optical trap: Ramsey spectroscopy to measure the energy decorrelation rate and echo spectroscopy to measure the collision rate. We obtain a value of 2.5 (3) for the collisional softness, in good agreement with previously reported numerical molecular dynamics simulations. This fundamental quantity was used to determine the $s$-wave scattering lengths of different atoms but has not been directly measured. We further show that the decay dynamics of the revival amplitudes in the echo experiment has a transition in its functional decay. The transition time is related to the softness of the collisions and provides yet another way to approximate it. These conclusions are supported by Monte Carlo simulations of the full echo dynamics. The methods presented here can allow measurements of a generalized softness parameter for other two-level quantum systems with discrete spectral fluctuations.
Spectroscopic properties of the molecular ions BeX^+ (X=Na, K, Rb): Forming cold molecular ions from an ion-atom mixture by stimulated Raman adiabatic process
Measurement of small photodestruction rates of cold, charged biomolecules in an ion trap
在这项工作中，我们展示了测量的光破坏率的冷冻，带电的生物分子。在超高真空条件下的离子阱中的分子离子的长期稳定存储允许测量小速率和验证速率在光破坏激光强度中是线性的。对有机化合物大黄酸（C30 H46 O 4）的单质子化分子进行测量，所述有机化合物大黄酸（C30 H46 O 4）通过使用不同强度的连续波UV激光（266 nm）解离。的分子被同情地冷却，同时捕获的激光冷却钡离子的平移温度低于150 mK。已测定的破坏速率小于0.05 s^-1，截面为（1.1 +/- 0.1）* 10^-17 cm ^2。可调谐紫外激光源的扩展将允许对各种冷复杂分子进行高分辨率解离光谱研究。
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）
Production and spectroscopy of cold radioactive molecules
California Institute of Technology（加州理工学院）；Yale University（耶鲁大学）；Johns Hopkins University（约翰斯·霍普金斯大学）；Massachusetts Institute of Technology（麻省理工学院）；Michigan State University（密歇根州立大学）
