Abstract: Spin defects in 2D materials such as ultrathin hexagonal boron nitride (hBN) have been found to be promising single-photon emitters and potential candidates for qubits. However, first-principles prediction of accurate defect properties in 2D materials remains challenging, mainly because of the highly anisotropic dielectric screening in 2D materials and strong many body interactions. This work shows how we solve the numerical convergence issues for charged defect properties in 2D materials at both the DFT and many body perturbation theory (GW/Bethe-Salpeter equation), and how we tackle the complex many body interactions including electron-electron, electron-phonon and defect-excitons for the excited state dynamics of spin defects in 2D materials through radiative and phonon-assisted nonradiative recombination. We are also developing first-principles spin dynamics through Lindblad dynamics for open quantum systems. We computed spin-phonon relaxation time (T1) including spin orbit and electron-phonon interaction explicitly and computed T1 for systems with and without Kramers degeneracy. Working in progress is to study ultrafast spin polarized carrier dynamics from first-principles. With our methods, we plan to design spin defects that have deep defect levels, weak electron-phonon coupling, high radiative recombination rates, and long spin relaxation and coherence time as future materials platforms for quantum information technologies. Biosketch： Dr. Yuan Ping’s research interest includes developing and employing theoretical and computational methods to understand and predict optical, carrier transport, and catalytic properties of materials from first-principles calculations. Ping’s recent research interests focus on first-principles methodology development on excited-state properties for solids and nanostructures, in particular, from many-body perturbation theory with improved numerical efficiency and accuracy, spin and charge dynamics of solid-state defects as spin qubits and single photon emitters for quantum information technology, and dopants’ effect on small polaron conduction in transition metal oxides. More information can be found at: http://www.chemistry.ucsc.edu/faculty/singleton.php?&singleton=true&cruz_id=yuanping http://yuanping.chemistry.ucsc.edu/
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