Suppression of heating rates in cryogenic surface-electrode ion traps

Dense arrays of trapped ions provide one way of scaling up ion trap quantum information processing. However, miniaturization of ion traps is currently limited by sharply increasing motional state decoherence at sub-100 mu m ion-electrode distances. We characterize heating rates in cryogenically cooled surface-electrode traps, with characteristic sizes in the 75 to 150 mu m range. Upon cooling to 6 K, the measured rates are suppressed by 7 orders of magnitude, 2 orders of magnitude below previously published data of similarly sized traps operated at room temperature. The observed noise depends strongly on the fabrication process, which suggests further improvements are possible.