The development of microfabricated ion traps towards quantum information and simulation

Hughes, Marcus (2013) The development of microfabricated ion traps towards quantum information and simulation. Doctoral thesis (PhD), University of Sussex.

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Abstract

Trapped ions within Paul traps have shown to be a promising architecture in the realisation
of a quantum information processor together with the ability of providing quantum
simulations. Linear Paul traps have demonstrated long coherence times with ions being
well isolated from the environment, single and multi-qubit gates and the high fidelity
detection of states. The scalability to large number of qubits, incorporating all the previous
achievements requires an array of linear ion traps. Microfabrication techniques allow
for fabrication and micron level accuracy of the trap electrode dimensions through photolithography
techniques.

The first part of this thesis presents the experiential setup and trapping of Yb+ ions
needed to test large ion trap arrays. This include vacuum systems that can host advanced
symmetric and asymmetric ion traps with up to 90 static voltage control electrodes.
Demonstration of a single trapped Yb+ ion within a two-layer macroscopic ion
trap is presented. with an ion-electrode distance of 310(10) μm. The anomalous heating
rate and spectral noise density of the trap was measured, a main form of decoherence
within ion traps.

The second half of this thesis presents the design and fabrication of multi-layer asymmetric
ion traps. This allows for isolated electrodes that cannot be accessed via surface
pathways, allowing for higher density of electrodes as well as creating novel trap designs
that allow for the potential of quantum simulations to be demonstrated. These include
two-dimensional lattices and ring trap designs in which the isolated electrodes provide
more control in the ion position.

For the microfabrication of these traps I present a novel high-aspect ratio electroplated electrode design that provides shielding of the dielectric layer. This provides a means to mitigate stray electric field due to charge build up on the dielectric surfaces. Electrical testing of the trap structures was performed to test bulk breakdown and surface flashover of the ion trap architectures. Results showed sufficient isolation between electrodes for both radio frequency and static breakdown. Surface flashover voltage measurements over the dielectric layer showed an improvement of more than double over previous results using
a new fabrication technique. This will allow for more powerful ion trap chips needed for the next generation of microfabricated ion trap arrays for scalable quantum technologies.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QC Physics > QC0170 Atomic physics. Constitution and properties of matter Including molecular physics, relativity, quantum theory, and solid state physics
Depositing User: Library Cataloguing
Date Deposited: 18 Jun 2013 13:33
Last Modified: 10 Sep 2015 14:09
URI: http://sro.sussex.ac.uk/id/eprint/45142

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