Simulation of vortex ion generation from a cold atom ion source

Abstract

Vortex waves with orbital angular momentum (OAM) have garnered significant attention since their appearance due to their unique properties. Vortex beams are experimentally demonstrated with photons, electrons, neutrons, and atoms. However, it is still challenging to make ions with large masses produce vortex states. This study describes a scheme for generating vortex ion beams with a cold atom ion source (CAIS). In CAIS, ions are obtained by near-threshold photoionization rubidium atoms in magneto-optical trap (MOT). We investigate the propagation properties of the rubidium ion beams through simulations. In the simulation, rubidium ions extract from the CAIS and generate vortices by diffracting with holograms, where the phase of the wavefunction is changed. We analyze in detail the structure and voltage of the CAIS and propose a feasible scheme for generating vortex ions in laboratory experiments. Additionally, we propose two alternatives, one is to reduce the velocity of the ions lower, another is to use a magnetic needle to generate vortex ions. These proposals provide a new pathway for future explorations into the generation and properties of vortex ion beams.

Keywords

• Vortex ion
• Cold atom
• Orbital angular momentum
• Charged particles optics