UC Berkeley

In this work, we present 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 confinement of single 40Ca+ ions at heights between 50 μm and 300 μm 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, trapping of vertical ion strings without excess micromotion, and may have applications for scalable quantum computers with surface ion traps.In our novel surface trap, we probe electric-field noise for ion-surface distances d between 50 μm and 300 μm in the normal and planar directions. We find the noise distance dependence to scale as d^−2.6 in our trap and a frequency dependence which is consistent with 1/f noise. Simulations of the electric-field noise specific to our trap geometry provide evidence that we are not limited by technical noise sources. Our distance scaling data is consistent with a noise correlation length of about 100 μm at the trap surface, and we discuss how patch potentials of this size would be modified by the electrode geometry. Finally, we achieve coupling between the motions of trapped ions separated by 620 μm. Our results are marked by the implementation of remote ion-ion interactions enhanced via an electrically floating metallic wire in an RF Paul trap. By tuning the confinement of each ion into resonance, we demonstrate classical energy exchange through sympathetic heating and heating rate reduction. The coupling interaction exchange time is extracted to be 22 ms. Practical improvements to the ion-wire-ion system are discussed, with realistic applications to sympathetic cooling of remote ions and more optimistic goals of coherent energy exchange at the single-quantum level. Our ion-wire-ion system establishes a building block for scalable trapped ion quantum computers and provides a tool for quantum communication between qubits of different types.