Surface trap with dc-tunable ion-electrode distance.

We describe the design, fabrication, and operation of a novel surface-electrode Paul trap that produces a radio-frequency-null along the axis perpendicular to the trap surface. This arrangement enables control of the vertical trapping potential and consequentially the ion-electrode distance via dc-electrodes only. We demonstrate the confinement of single Ca ions at heights between 50 m and 300 m above planar copper-coated aluminum electrodes. Laser-cooling and coherent operations are performed on both the planar and vertical motional modes. This architecture provides a platform for precision electric-field noise detection and trapping of vertical ion strings without excess micromotion and may have applications for scalable quantum computers with surface ion traps.