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 µm ion-electrode distances. We characterize heating rates in cryogenically cooled surface-electrode traps, with characteristic sizes in 75 µm to 150 µm range. Upon cooling to 6 K, the measured rates are suppressed by 7 orders of magnitude, two orders of magnitude below previously published data of similarly sized traps operated at room temperature. The observed noise depends strongly on fabrication process, which suggests further improvements are possible.PACS numbers: 32.80. Pj, 39.10.+j, 42.50.Vk Quantum information processing offers a tantalizing possibility of a significant speedup in execution of certain algorithms [1,2], as well as enabling previously unmanageable simulations of large quantum systems [3,4]. One of the most promising avenues towards practical quantum computation uses trapped ions as qubits. Interaction between qubits can be mediated by superconductive wires [5], photons [6,7] or by shared phonon modes [8]. The last scheme has been most successful so far, having demonstrated one and two qubit gates [9], teleportation [10,11], error correction[12] and shuttling [13]. Scaling of these experiments to a large number of ions will require arrays of small traps, on the order of 10 µm, to achieve dense qubit packing, improve the gate speed and reduce the time necessary to shuttle ions between different traps in the array [14,15,16,17]. Micro-fabrication techniques have been successfully used to fabricate a new generation of ion traps, demonstrating trap sizes down to 30 µm [18,19,20]. However, as the trap size is decreased, ion heating and decoherence of the motional quantum state increases rapidly, approximately as the fourth power of the trap size [21,22,23]. At currently observed values, the heating rate in a 10 µm trap would exceed 10 6 quanta/s, precluding ground-state cooling or qubit operations mediated by the motional state.The strong distance dependence of the heating rate suggests that the electric field noise is generated by surface charge fluctuations, which are small compared to the distance to the ion. Charge noise is also observed in condensed matter systems, where device fabrication has proven critical in reducing the problem [24,25]. Similar advances in ion traps are impeded by lack of data and models accurately predicting measured noise [26,27,28]. The charge fluctuations have been demonstrated to be thermally driven, providing another plausible route to reduce the heating. Cooling of the electrodes to 150 K has been shown to significantly decrease the heating rate [23].In this Letter, we present the first measurements of heating rates in ion traps cooled to 6 K. We designed and built a range of surface-electrode traps, in which we are able to cool a single ion to motional ground state with high fidelity and observe heating on a quantum level. Although the traps h...

Electric field noise from fluctuating patch potentials is a significant problem for a broad range of precision experiments, including trapped ion quantum computation and single spin detection. Recent results demonstrated strong suppression of this noise by cryogenic cooling, suggesting an underlying thermal process. We present measurements characterizing the temperature and frequency dependence of the noise from 7 to 100 K, using a single Sr+ ion trapped 75 mum above the surface of a gold plated surface electrode ion trap. The noise amplitude is observed to have an approximate 1/f spectrum around 1 MHz, and grows rapidly with temperature as T;{beta} for beta from 2 to 4. The data are consistent with microfabricated cantilever measurements of noncontact friction but do not extrapolate to the dc measurements with neutral atoms or contact potential probes.

We present a novel system where an optical cavity is integrated with a microfabricated planar-electrode ion trap. The trap electrodes produce a tunable periodic potential allowing the trapping of up to 50 separate ion chains aligned with the cavity and spaced by 160 µm in a one-dimensional array along the cavity axis. Each chain can contain up to 20 individually addressable Yb + ions coupled to the cavity mode. We demonstrate deterministic distribution of ions between the sites of the electrostatic periodic potential and control of the ion-cavity coupling. The measured strength of this coupling should allow access to the strong collective coupling regime with 10 ions. The optical cavity could serve as a quantum information bus between ions or be used to generate a strong wavelength-scale periodic optical potential.