Conlon, Aaron (2023) Generalised Braiding of Anyonic Excitations and Topological Quantum Computation. PhD thesis, National University of Ireland Maynooth.
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Abstract
This thesis investigates various topological phases of matter in two-dimensional and
quasi one-dimensional systems. These exotic states of matter have applications in
topological quantum computation; which is an inherently fault-tolerant quantum
computation scheme. In these schemes, computations are implemented by braiding
anyonic excitations. In this thesis we examine three aspects of braiding: braiding
of anyonic excitations on graphs, topological lattice models, and non-adiabatic
perturbations of a qubit constructed from Majorana bound states.
In the first part of the thesis we introduce a universal framework to discuss the
braiding of anyonic excitations on graphs as a model of a quantum wire network. We
show that many features of the planar algebraic theory of anyons may be extended
to graphs. In this direction, we introduce graph hexagon equations, a generalisation
of the planar hexagon equations and demonstrate that this framework has several
similarities and differences from its planar counterpart. Notably, depending on the
graph, we find solutions that do not exist in the planar theory. We study this
framework on a variety of graphs and tabulate solutions.
In the second part, we investigated non-adiabatic perturbations of a topological
memory that consists of two p-wave superconducting wires separated by a nontopological
junction. We consider noise in the potential creating the non-trivial
topological phase and also the effect of shuttling the Majoranas, a necessary step in
braiding. We examine a mechanism for bit and phase flip errors where excitations
from one wire tunnel through a junction into another wire, we also outline a scheme
that utilises disorder to minimise such situations.
In the final part of the thesis, we construct a modified toric code from Hopf algebra
gauge theory. We find that introducing a non-trivial quasitriangular structure on the
gauge group changes the identification of braiding statistics in the quantum double,
although it is of the same topological order as the toric code. In particular, when
the gauge group is CZN we can interpret this as a form of flux attachment, where
under exchange, the electric charges behave as if they have fluxes attached.
Item Type: | Thesis (PhD) |
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Keywords: | Generalised Braiding; Anyonic Excitations; Topological Quantum Computation; |
Academic Unit: | Faculty of Science and Engineering > Theoretical Physics |
Item ID: | 17805 |
Depositing User: | IR eTheses |
Date Deposited: | 09 Nov 2023 12:28 |
URI: | https://mural.maynoothuniversity.ie/id/eprint/17805 |
Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
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