Spin state tailoring of quantum dot spins for quantum information processing

Student thesis: Doctoral Thesis

Abstract

Individual quantum dots can be efficiently harnessed as matter-based spin-qubits resulting in applications across the field of quantum information processing. In this work, single-qubit operations of quantum dot spin states are shown through a range of coherent control experiments demonstrating that these systems have great potential. The system structure of the quantum dot can be varied through application of a range of electric and magnetic fields. This work extended the existing body of knowledge through characterization of the system properties and further by experimental demonstrations under non-standard magnetic field configurations. The initial objective required developing a state-of-the-art experiment with capabilities to manipulate and control individual quantum dot spin-qubits. This involved building and optimizing a cryo-magnetic environment alongside a complex optical excitation system using pulsed and continuous wave lasers. Upon completion, the remainder of this work demonstrated coherent control between the ground-state spins confined to a quantum dot under both standard and non-standard magnetic fields. The system was characterized under oblique magnetic field configurations which mix the properties common to the Voigt and Faraday geometries (the two most common magnetic field configurations). After a successful analysis, further experiments revealed the spin-qubits under non-standard field configurations can be manipulated with relative ease and only a minor impact on the efficacy of operations. Coherent control experiments were demonstrated with promising clarity and precision. Single-qubit tomography showed high fidelity initialization and reconstruction of the initial state of the spin-qubit. Finally, verification of geometric phase gates under oblique configurations confirms further methods with which to control the spin-qubit state space. By extending the body of knowledge under non-standard magnetic fields this work can directly apply to a wide variety of spin-based quantum systems grown using non-standard geometries such as pyramidal 1-1-1 quantum dots. Additionally, the enhanced understanding of quantum dots under non-standard magnetic field configurations allows more flexibility when adapting quantum dots for further applications and future research.
Date of Award6 Sept 2024
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsEPSRC (Engineering and Physical Sciences Research Council)
SupervisorKonstantinos Lagoudakis (Supervisor) & Robert Martin (Supervisor)

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