Design and fabrication of high magnetic field gradients towards fault tolerant two-qubit gates with trapped ions using long-wavelength radiation

Standing, Eamon Daniel (2017) Design and fabrication of high magnetic field gradients towards fault tolerant two-qubit gates with trapped ions using long-wavelength radiation. Doctoral thesis (PhD), University of Sussex.

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In this thesis, I discuss coherent manipulation of a trapped ytterbium ion using long
wavelength radiation and the results of experiments towards the performance of a two-ion
entanglement gate using a static magnetic field gradient of 23.3(6) T/m to create coupling
between an ion's internal state and its motion.

After using these experiments to explain the requirements for high-fidelity entanglement
operations, I continue by examining existing methods for creating this gradient, the
current limiting factor in producing the highest fidelity operations. This includes a full
characterisation of the gradients produced by symmetric scheme permanent magnets and
buried current carrying wires including development of scaling laws in order to create
optimum gradients for a given trap geometry.

I continue by proposing a new method by which extremely high gradients over 100 T/m
can be created for planar chip traps with minimal modification to an existing experiment.
These gradients are tailored for axial as well as radial entanglement schemes and aim to
show that the technology exists in order to produce a two-qubit gate over the fault tolerant

Subsequently, I discuss the implementation of this new scheme in an experiment before
constructing the apparatus to accurately align a chip with these magnets and documenting
their installation into two new experimental setups. This includes a preliminary measurement
of the gradient produced by an imperfect setup outside of vacuum which verifies
those simulated at ~ 110 T/m.

Lastly, I discuss the prospects of on-chip magnetic materials and propose a new method
which when sufficiently developed should allow for high magnetic field gradients to be
produced on-chip at higher ion heights than when solely using current carrying wires.
Additionally this scheme should allow for switchable gradients with maximised stability
in geometries previously not possible to create.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QC Physics > QC0770 Nuclear and particle physics. Atomic energy. Radioactivity > QC0794.95 Radioactivity and radioactive substances
Depositing User: Library Cataloguing
Date Deposited: 25 Jul 2017 08:51
Last Modified: 25 Jul 2017 08:51

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