Collaborative Research: RUI: Atomic Collisions with Trapped Ions in Ultracold Hybrid Systems

Hybrid systems consisting of trapped ions immersed in an ultracold gas of neutral atoms offer exciting new opportunities for quantum science and technology that benefit from decades of advances made with each of these respective system constituents. While collision processes between ions and neutral atoms in free space have received theoretical attention, a fully quantum mechanical description of such collisions that includes the ion confinement remains largely unexplored despite the fact that recent experimental advances have realized such systems in the lab.

The research team will develop a fully quantum mechanical description of collision processes between neutral atoms and trapped ions. Such a theory is necessary to inform ongoing and near-future experiments, paving the way for ultracold hybrid atom-ion systems as avenues to study atom-ion chemistry, probes of many-body physics in atomic gases, or as platforms for other applications in quantum information science.

This work will be carried out at primarily undergraduate institutions, introducing students of diverse backgrounds to methodologies in modern theoretical physics, and providing undergraduates with an opportunity to make meaningful contributions to modern scientific research.

In particular, the research team will investigate collisional resonances that arise as a consequence of the ion confinement, and use insights gained from the study of single ion systems to guide the treatment of systems with two or more ions. The proposed collision theory constitutes a marriage of two powerful methodologies that have each played a pivotal role in scattering theory and few-body physics: multichannel quantum defect theory (MQDT), and the adiabatic hyperspherical method.

A successful integration of these methodologies could potentially be applied to other few-body systems well beyond the atom-ion problem. The goals of the project are to (1) refine a preliminary one-dimensional model based on single-channel atom-ion interactions with ionic confinement and extend it to three dimensions, computing observables such as elastic and inelastic collision rates and time delays. (2) Incorporate multichannel interactions that include the internal magnetic structure of the collision partners and investigate the consequences of ion trap micromotion. (3) Building on insights from preceding efforts, formulate a model for hybrid systems of atoms and multiple ions, with particular emphasis on understanding how a collision event couples to the entangled motional state of an ion crystal.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.