Stick-Slip Dynamics of a Stressed Ion Crystal

We study the control of the rotation of a laser-cooled ion crystal in a Penning trap by a rotating electric field perturbation. We show that application of a small torque produces sudden angular jumps or “slips” of the crystal orientation spaced by intervals when the crystal is phase locked or “stuck” relative to the rotating perturbation. The distribution of angular slips is described by a power law, where the power-law exponent depends on the applied torque. We believe this system is driven by a constant force and small perturbations or thermal effects trigger the slips.