High-energy-resolution measurements of an ultracold-atom–ion collisional cross section

The cross section of a given process fundamentally quantifies the probability for that to occur. In quantum regime low energies, can vary strongly with collision energy due effects. Here, we report on method directly measure atom-ion collisional in range 0.2-12 mK$\cdot$ k$_B$, by shuttling ultracold atoms trapped an optical-lattice across radio-frequency ion. this method, average number collisions per experiment is below one such resolution not limited broad (power-law) steady-state distribution. estimate 200 $\mu$K$\cdot$k$_B$, drifts ion's excess micromotion compensation and be reduced 10's $\mu$K$\cdot$k$_B$ regime. This order-of-magnitude better than previous experiments measuring cold dependence. We used our dependence inelastic sections non-adiabatic Electronic-Excitation-Exchange (EEE) Spin-Orbit Change (SOC) processes. found measured range, EEE SOC statistically agree classical Langevin section. allows various processes opens up possibilities search signatures as shape-resonances.