First-principles studying for quantum defects in cubic boron nitride

Abstract

The quest for novel solid-state quantum bits (qubits) is pivotal in the development of next-generation quantum technologies. In this study, employing first-principles simulations based on density functional theory, we have scrutinized the quantum defect properties of four complex defects within cubic boron nitride (cBN) crystals; they are formed by a Boron vacancy and an adjacent impurity–where the impurity atom can be either an Oxygen substituting a Nitrogen, or a Carbon, Silicon, or Germanium substituting a Boron. We assess key qubit-related parameters including the zero-phonon line, zero-field splitting, and hyperfine interaction, and compare our findings with both experimental data and previous theoretical studies. Our results indicate that these defects exhibit significant promise as quantum bits, potentially surpassing the capabilities of the nitrogen-vacancy complex center in diamond, particularly in the context of quantum networks or bio-nanosensors that leverage telecom wavelength quantum emissions. Furthermore, we have conducted an analysis of the thermodynamic stability of these defects and proposed possible strategies to enhance their stability in experimental settings. The collective insights gained from this study pave the way for more adaptable strategies in the design and engineering of quantum bits in cBN for advanced quantum technologies.