Aspects of decoherence in qubit systems
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Cox, Timothy
issued: 2019-04-29T17:38:46Z
issued: 2019
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: We present a theoretical discussion of various aspects of the dynamics of information in quantum systems of qubits. We begin by reviewing ideas about entanglement and information in systems of qubits, different models for realistic qubits coupled to an external environment, how this causes the loss of information stored in qubits, and some practical designs for qubits that have been created. Then we study how the state of many-body systems can be decomposed in terms of its different subsystems and derived a hierarchy of equations describing the motion of these different parts. We show that in a qubit system, the central objects in this hierarchy are correlators between different components of different qubits. Systems where the environment coupled to a central qubit is a "spin bath'' of environmental qubits are then considered in detail and we find that information lost by the central qubit is transferred via a cascade to higher and higher order correlations with the environment. We discuses this process in the realistic example of an "Feâ'' magnetic molecule qubit. Finally we discuss simple models of the dynamics of many entangled qubits.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/69984
note: Aspects of Decoherence in QubitSystemsbyTimothy CoxB.Sc. (Hons), Victoria University of Wellington, 2007M.Sc., McGill University, 2010A THESIS SUBMITTED IN PARTIAL FULFILMENT OFTHE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYinThe Faculty of Graduate and Postdoctoral Studies(Physics)THE UNIVERSITY OF BRITISH COLUMBIA(Vancouver)April 2019c© Timothy Cox, 2019iiThe following individuals certify that they have read, and recommend to the Facultyof Graduate and Postdoctoral Studies for acceptance, the thesis entitled:Aspects of Decoherence in Qubit Systemssubmitted by Timothy Cox in partial fulfillment of the requirements for the degreeof Doctor of Philosophy in Physics.Examining Committee:Professor Philip C. E. Stamp, PhysicsSupervisorProfessor Mona I. Berciu, PhysicsSupervisory Committee MemberProfessor Gordon W. Semenoff, PhysicsSupervisory Committee MemberProfessor Jim Bryan, MathematicsUniversity ExaminerProfessor Ian Keith Affleck, PhysicsUniversity ExaminerAdditional Supervisory Committee Members:Associate Professor Joshua Folk, PhysicsSupervisory Committee MemberProfessor Fei Zhou, PhysicsSupervisory Committee MemberiiiAbstractWe present a theoretical discussion of various aspects of the dynamics of informationin quantum systems of qubits. We begin by reviewing ideas about entanglement andinformation in systems of qubits, different models for realistic qubits coupled to anexternal environment, how this causes the loss of information stored in qubits, andsome practical designs for qubits that have been created. Then we study how thestate of many-body systems can be decomposed in terms of its different subsystemsand derived a hierarchy of equations describing the motion of these different parts.We show that in a qubit system, the central objects in this hierarchy are correlatorsbetween different components of different qubits. Systems where the environmentcoupled to a central qubit is a âspin bathâ of environmental qubits are then consi-dered in detail and we…
has type: Thesis/Dissertation
date issued: 2019-09
is shown at: 10.14288/1.0378509
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/69984