Manipulation and Decoherence of Spin-valley Qubits in Monolayer Transition Metal Dichalcogenide Nanostructures
Abstract
Scientific Objectives: In this project, design of spin-valley qubits based on monolayer transition metal dichalcogenide (TMDC) nanostructures will be investigated with valley Hall effect as the theoretical basis. In particular, the manipulation as well as decoherence mechanisms of the spin-valley qubits will be studied. Essential to the spin-valley qubit is the quantum mechanical interaction between light and the ensemble of electrons in the coupled system. Its energy-level structure, optical manipulation, and temporal evolution on the Bloch sphere is one of the themes of this work. As an alternative to the optical valley polarization, the possibility of spin-injected polarization will also be explored for qubit initialization and manipulation. Another objective of this project is the study of possible decoherence mechanisms in the spin-valley qubits. Qubit decoherence from a variety of practical factors will be investigated. Methods to be employed: First-principle calculations based on density functional theory utilizing the hybrid or gradient potentials will be performed to investigate the electronic structure of the surface states. Afterwards, the calculation results will be applied to obtain computationally efficient models to investigate the spin-transport properties and light-spin interaction mechanisms. These models are primarily based on the Kubo formula from the linear response theory, as well as the non-equilibrium GreenÕs function formalism that is coupled to a Floquet Hamiltonian describing a periodically driven system. These precise theoretical calculations will be employed to study the spin-dephasing and scattering mechanisms. Significance of the proposed effort to the advancement of knowledge: Monolayer TMDCs are a new class of materials with unique features, which have prompted suggestions of their great potentials as spin-valley qubits: the spin and valley pseudospin of a single electron can be a promising information carrier. However, research on the spin-valley qubits is still at a nascent state. This project is to address this knowledge gap and investigate the potentials of spin-valley qubits, especially its control/manipulation and decoherence. The proposed work encompasses research ranging from material physics, surface science, carrier transport theory, light matter interaction and device physics. As a result, the multi-disciplinary investigation can potentially lead to significant advances in different areas, ranging from fundamental physics to potentially transformative computing architectures. In particular, in-depth understanding of the manipulation and decoherence mechanisms of monolayer TMDC nanostructures will provide direct guidelines for the future device structure designs in quantum information systems.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 25, 2019
- Source ID
- W911NF1910309
Entities
People
- Junxia Shi
Organizations
- Army Contracting Command
- United States Army
- University of Illinois at Chicago