Quantum networks play an indispensable role in quantum information tasks such as secure communications, enhanced quantum sensing, and distributed computing. In recent years several platforms are being developed for such tasks, witnessing breakthrough technological advancement in terms of fabrication techniques, precise control methods, and information transfer. Among the most mature and promising platforms are color centers in solids. These systems provide an optically active electronic spin and long-lived nuclear spins for information storage. The first part of this dissertation is concerned with error mechanisms in the control of electronic and nuclear spins. First, I will focus on control protocols for improved electron-spin rotations tailored to specific color centers in diamond. I will then discuss how to manipulate the entanglement between the electron and the always-coupled nuclear spin register. I will describe a general formalism to quantify and control the generation of en- tanglement in an arbitrarily large nuclear spin register. This formalism incorporates exactly the dynamics with unwanted nuclei, and quantifies the performance of entangling gates in the presence of unwanted residual entanglement links. Using experimental parameters from a well-characterized multinuclear spin register, I will show that preparation of multipartite entanglement in a single-shot is possible, which drastically reduces the total gate time of conventional protocols. Then, I will present a new formalism for describing all-way entanglement and show how to design gates that prepare GHZM states. I will show how to incorporate errors such as unwanted correlations, electronic dephasing errors or pulse control errors. The second part of this thesis focuses on the preparation of all-photonic graph states from a few quantum emitters. I will introduce heuristic algorithms that exploit graph theory concepts in order to reduce the entangling gate counts, and also discuss the role of locally equivalent graphs in the optimization of the generation circuits. / Doctor of Philosophy / Quantum information science emerged by combining ideas and principles of information theory, nanoscale engineering, photonics, atomic and solid-state physics in a unified effort to realize and fabricate efficient quantum-based architectures. Spin-based solid-state quantum computers are one of the leading candidates for quantum architectures. For these types of devices, the quantum bit of information can be encoded in the spin states of electron/nuclear memories, while the logical operations are performed by driving transitions between a multi- level spin structure. In this thesis, I will describe the role of color centers for quantum computations and networking. I will explain the error sources and dynamics of SiV− and SnV− color centers in diamond and show how to drive with high fidelity optical rotations of their spin states. Additionally, I will explain how periodic driving of the electronic spin can serve as a method to control the nuclear spin memories and show how to precisely prepare multipartite entangled states within an arbitrarily large electron-nuclear spin register. Lastly, I will focus on the preparation of all-photonic graph states and show how to prepare them with optimal resources.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/119501 |
| Date | 25 June 2024 |
| Creators | Takou, Evangelia |
| Contributors | Physics, Economou, Sophia Eleftherios, Heremans, Jean Joseph, Barnes, Edwin Fleming, Park, Kyungwha |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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