Understanding Electron-Nuclear and Electron-Electron Spin Dynamics for Quantum Information Science and Beyond

Yu, Chung-Jui

doi:https://doi.org/10.21985/n2-8d36-f475

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Understanding Electron-Nuclear and Electron-Electron Spin Dynamics for Quantum Information Science and Beyond

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The era of quantum information science (QIS) can usher revolutionary new capabilities ranging from quantum computation to quantum sensing. At the core of these technologies is the fundamental unit of QIS, the quantum bit or qubit. The power of qubits over their classical counterparts lies in their ability to be placed in a superposition of the classical states “0” and “1” and harness quantum entanglement. The last decade has seen unprecedented control over the quantum mechanical properties of electronic spins in coordination complexes, which has emerged as a class of promising qubit candidates. The inherent synthetic versatility of this class of qubits has enabled atomic control over the molecule’s spin properties, which has led to the development of fundamental synthetic design principles governing molecular qubit properties. In this dissertation, I discuss efforts to address two challenges facing molecular electronic spin-based qubits: long coherence times (T2) and scalability to many-qubit architectures. Chapter 1 introduces coordination complexes as electronic spin-based qubits and their outstanding challenges. Chapter 2 details the generality of nuclear spin-free synthetic design in engendering over 100 μs coherence times across a series of vanadyl coordination complexes. Chapter 3 explores the relationship between electron-nuclear spin coupling strength and nuclear spin effects on T2 through a series of vanadyl complexes with precisely designed V-1H distances. Chapter 4 applies the lessons learned on electronic-nuclear spin dynamics to dynamic nuclear polarization (DNP) with electronically anisotropic vanadyl complexes. Chapter 5 examines the role of electronic-electronic spin coupling interactions on the coherence times of an atomically precise array of copper porphyrinic qubits in a metal-organic framework (MOF). Chapter 6 builds upon this work by investigating the interplay between spin-spin and phonon-mediated relaxation processes in a series of MOFs with varied metal nodes and organic linkers. Lastly, chapter 7 discusses the role of molecular qubits towards quantum sensing, an exciting area within QIS that holds enormous potential for molecular systems to make immediate contributions in fields spanning molecular biology to atomic physics.

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