Trapping and cooling two-dimensional crystals of barium ions

Abstract

The design and characterization of a trap specifically designed to create 2D crystals of trappedbarium ions is presented. The trap is used to study the Doppler cooling of 2D crystals. Ions in RF traps are subject to micromotion, a time-dependent driven motion caused by the RF fields themselves. This micromotion leads to Doppler shifts in laser-ion interactions. Laser cooling of 2D crystals can become increasingly difficult as crystals get bigger and are therefore subjected to more micromotion. We explore two methods for Doppler cooling in the presence of significant micromotion. The first method is to power broaden and detune cooling beams, reducing the distortions on atomic lineshape due to micromotion. The second method is to use nanosecond pulses of laser light synchronized with the trap RF in order to selectively cool the ions over a narrow range of velocities.