550 research outputs found
Increased surface flashover voltage in microfabricated devices
With the demand for improved performance in microfabricated devices, the
necessity to apply greater electric fields and voltages becomes evident. When
operating in vacuum, the voltage is typically limited by surface flashover
forming along the surface of a dielectric. By modifying the fabrication process
we have discovered it is possible to more than double the flashover voltage.
Our finding has significant impact on the realization of next-generation micro-
and nano-fabricated devices and for the fabrication of on-chip ion trap arrays
for the realization of scalable ion quantum technology
Planar Ion Trap Geometry for Microfabrication
We describe a novel high aspect ratio radiofrequency linear ion trap geometry
that is amenable to modern microfabrication techniques. The ion trap electrode
structure consists of a pair of stacked conducting cantilevers resulting in
confining fields that take the form of fringe fields from parallel plate
capacitors. The confining potentials are modeled both analytically and
numerically. This ion trap geometry may form the basis for large scale quantum
computers or parallel quadrupole mass spectrometers.
PACS: 39.25.+k, 03.67.Lx, 07.75.+h, 07.10+CmComment: 14 pages, 16 figure
Optimisation of two-dimensional ion trap arrays for quantum simulation
The optimisation of two-dimensional (2D) lattice ion trap geometries for
trapped ion quantum simulation is investigated. The geometry is optimised for
the highest ratio of ion-ion interaction rate to decoherence rate. To calculate
the electric field of such array geometries a numerical simulation based on a
"Biot-Savart like law" method is used. In this article we will focus on square,
hexagonal and centre rectangular lattices for optimisation. A method for
maximising the homogeneity of trapping site properties over an array is
presented for arrays of a range of sizes. We show how both the polygon radii
and separations scale to optimise the ratio between the interaction and
decoherence rate. The optimal polygon radius and separation for a 2D lattice is
found to be a function of the ratio between rf voltage and drive frequency
applied to the array. We then provide a case study for 171Yb+ ions to show how
a two-dimensional quantum simulator array could be designed
Scaling and Suppression of Anomalous Heating in Ion Traps
We measure and characterize anomalous motional heating of an atomic ion confined in the lowest quantum levels of a novel rf ion trap that features moveable electrodes. The scaling of heating with electrode proximity is measured, and when the electrodes are cooled from 300 to 150 K, the heating rate is suppressed by an order of magnitude. This provides direct evidence that anomalous motional heating of trapped ions stems from microscopic noisy potentials on the electrodes that are thermally driven. These observations are relevant to decoherence in quantum information processing schemes based on trapped ions and perhaps other charge-based quantum systems
Supporting Adaptive Workflows in Advanced Application Environments
The need for supporting adaptive workflows (WFs) is widely recognized. For many business processes (BPs) it is nearly impossible to consider all possible task sequences already at the design level. Besides this, ongoing business cases may also have to be adapted to organizational and functional changes in their environment. A basic step towards adaptive workflow management systems (WfMSs) is the support of run-time WF specification as well as of dynamic WF changes. Such changes may affect only a single active WF instance or may affect multiple instances of a particular WF type. To adequately support adaptive WFs, it is important to understand why processes change and which kinds of changes may occur. In this paper we use clinical application scenarios to explain and to elaborate the functionality needed to support dynamic WF changes in an advanced application environment. The paper addresses conceptual issues related to ad hoc changes of a single WF instance on the one hand, and it discusses issues related to WF schema changes and their propagation to its active instances on the other hand. We show that the different levels of changes must be considered in conjunction and we use the ADEPT concepts to illustrate how an integrated approach could look like
Dynamical localization of matter wave solitons in managed barrier potentials
The bright matter wave soliton propagation through a barrier with a rapidly
oscillating position is investigated. The averaged over rapid oscillations
Gross-Pitaevskii (GP) equation is derived. It is shown that the soliton is
dynamically trapped by the effective double-barrier.
The analytical predictions for the soliton effective dynamics is confirmed by
the numerical simulations of the full GP equation.Comment: 10 pages, 6 figure
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