Observation of trap-assisted formation of atom-ion bound states

Abstract

Pairs of free particles cannot form bound states in elastic collision due to momentum and energy conservation. In many ultracold experiments, however, the particles collide in the presence of an external trapping potential which can couple the center-of-mass and relative motions and assist the formation of bound-states. Here, we report on observation of weakly bound molecular states formed between one ultracold ${}^{87}$Rb atom and a single trapped ${}^{88}$Sr${}^{+}$ ion in the presence of a linear Paul trap. We show that bound states can form efficiently in binary collisions, and enhance the rate of inelastic processes. By observing electronic spin-exchange rate, we study the dependence of these bound states on the collision energy and magnetic field and extract the average molecular binding energy $E_{\text{bind}}=0.7(1)$ mK$\cdot k_B$ and the mean lifetime of the molecule $\tau =0.5(1)\mu$s, with good agreement with molecular-dynamics simulations. Our simulations predict a highly unusual power-law distribution of molecular lifetimes with a mean that is dominated by extreme, long-lived, events. The dependence of the molecular properties on the trapping parameters opens new avenues to study and control ultracold collisions.

17 pages, 12 figures

References in corpus (9)

• Controlling chemical reactions of a single particle
• Observation of Feshbach resonances between a single ion and ultracold atoms
• Controlled collisions of a single atom and ion guided by movable trapping potentials
• Observation of collisions between cold Li atoms and Yb${}^{+}$ ions
• Kinetics of a single trapped ion in an ultracold buffer gas
• Direct Measurements of Collisional Dynamics in Cold Atom Triads
• Quantum-Logic Detection of Chemical Reactions
• Trap-assisted complexes in cold atom-ion collisions
• Observation of confinement-induced resonances in a 3D lattice

Cited by in corpus (12)

• Cold trapped molecular ions and hybrid platforms for ions and neutral particles
• Multi-site Integrated Optical Addressing of Trapped Ions
• Observation of confinement-induced resonances in a 3D lattice
• Quantum control of ion-atom collisions beyond the ultracold regime
• Exploring atom-ion Feshbach resonances below the s-wave limit
• Fermi polaron in atom-ion hybrid systems
• Cold hybrid electrical-optical ion trap
• Trap-induced atom-ion complexes: a time-independent approach
• Chaotic scattering and heating in cold ion-atom collisions: two sides of the same coin
• Quantum suppression of cold reactions far from the s-wave energy limit
• Ultracold collisions of a neutral atom with a trapped ion in 1D
• Cooling dynamics of a free ion in a Bose-Einstein condensate