Heating of trapped ions from the quantum ground state

We have investigated motional heating of laser-cooled Be ions held in radio-frequency ~Paul! traps. We have measured heating rates in a variety of traps with different geometries, electrode materials, and characteristic sizes. The results show that heating is due to electric-field noise from the trap electrodes that exerts a stochastic fluctuating force on the ion. The scaling of the heating rate with trap size is much stronger than that expected from a spatially uniform noise source on the electrodes ~such as Johnson noise from external circuits!, indicating that a microscopic uncorrelated noise source on the electrodes ~such as fluctuating patch-potential fields! is a more likely candidate for the source of heating.