Linear ion trap imperfection and the compensation of excess micromotion

Quantum computing requires ultracold ions in a ground vibrational state, which is achieved by sideband cooling. We report our recent efforts towards the Lamb-Dicke regime which is a prerequisite of sideband cooling. We first analyse the possible imperfection in our linear ion trap setup and then demonstrate how to suppress the imperfection by compensating the excess micromotion of the ions. The ions, after the micromotion compensation, are estimated to be very close to the Doppler-cooling limit.