Exploring Quantum Defects in Hexagonal Boron Nitride: A DFT+DMRG Approach.

• Grant number: 25/06160-7
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Vivian Vanessa França Henn
• Grantee: Ramiro Marcelo dos Santos
• Supervisor: Anderson Janotti
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Institution abroad: University of Delaware (UD), United States
• Associated to the scholarship: 24/10789-5 - Development and optimization of density functionals for the Hubbard model, BP.PD

Abstract

Two-dimensional van der Waals materials offer great opportunities for the development of quantum information science and technology. They serve as hosts of defects for quantum sensing, single-photon emitters, and qubits. Among the most explored van der Waals materials, hexagonal boron nitride (h-BN) stands out due to its large band gap and high structural stability. Point defects in h-BN (intrinsic or impurities) have been invoked to exhibit interesting functionalities due to atomic-like orbital/spin wavefunctions, such as sources of single-photon emission, qubits, and magnetic sensors. In this project, we will investigate defects in monolayer, few layers, and bulk h-BN, searching for candidates for single-photon emitters, qubits, quantum sensing, and quantum entanglement. Besides intrinsic defects, we will consider supposedly simple impurities such as C and S and impurities that are certain to display strong electron correlation effects, such as transition metals with partially occupied d shells and lanthanides, displaying partially occupied f shells. The investigations will involve first-principles calculations based on the density functional theory and hybrid functionals for total energies and structure relaxations and a quantum embedding method based on a multiorbital Hubbard model with maximally localized Wannier functions and density matrix renormalization group (DMRG) to determine the ground-state and excited properties. We will include electron-phonon coupling to determine radiative line shapes, will calculate non-radiative recombination rates, and analyze the role of defect-induced electronic states in modulating quantum entanglement and spin correlation. We expect our findings to provide insights into the design of defect-engineered 2D materials for future quantum information technologies.