In recent years, the AMO scientific community has shown an increasing interest in hybrid quantum systems, i.e. composite systems made of two different quantum systems that interact in the same experimental setup. When the two systems are isolated, they undergo evolutions governed by their unperturbed Hamiltonians. However, when these systems interact, the evolutions of both systems are perturbed, leading to the emergence of new physical properties and behaviours. An ultracold gas of neutral atoms interacting with one or a few trapped ions compose an atom-ion hybrid quantum system, which can be used as a new platform to study quantum physics and to realize new quantum technologies. Atom-ion physics is strongly affected by the charge-induced dipole interaction potential, which is two orders of magnitudes longer-ranged than the Van der Waals potential responsible of atom-atom interactions.
The quantum hybrid system that we are currently setting up at LENS will be composed by a Lithium degenerate gas and one or more Barium ions. The aim of this project is to realize a quantum hybrid system of atoms and ions in the ultracold regime, i.e. at temperatures for which atom-ion collisions are in the s-wave scattering regime. In this regime it will be possible to search novel atom-ion Feshbach resonances, which have been predicted but never observed so far. This goal will be reached by the development of a new ion trap that combines a static electric quadrupole and an optical lattice along the quadrupole anti-trapping direction, while the atoms will be trapped in an optical dipole trap.
With this novel experimental setup we plan to achieve sympathetic cooling of the ions to the ground state after their immersion into the Lithium ultracold gas, and to exploit the coherent coupling between atoms and ions to investigate the physics of a many-body system in the presence of one or a few localized impurities.