Group seminar at MPQ and Zoom: Trap-assisted bound states and chaos in ultracold atom-ion collisions

Meirav Pinkas, Weizmann Institute of Science, Israel
Group seminar at MPQ lecture hall and Zoom
Wednesday, October 4, 10:00am (MEZ)

A hybrid system combining ultracold atoms and ions can be used for studying collisions between a single pair of particles in the ultracold regime. In this talk, I will present the observation of trap-assisted bound states in ultracold atom-ion collisions. In free space, two free particles cannot be bound in an elastic binary collision due to energy and momentum conservation. However, since the ion is strongly trapped, the trap can couple the center-of-mass and relative motion and lead to a short-lived bound state. We show that bound states can be formed efficiently in binary collisions of 88Sr+ ion and 87Rb atom by measuring enhancement of electronic spin-exchange rate. In addition, numerical simulations show that collisions between a free atom and a trapped ion have high sensitivity to initial conditions, characterized by a fractal dimension. Chaos also leads to a molecular lifetime distribution with a power-law tail of long-lived events, which might be observed experimentally. These numerical observations suggest that signatures of chaos might also appear at the quantum limit, such as a Wigner-Dyson distribution of resonances.