A paramagnetic neutral C_BV_N center in hexagonal boron nitride monolayer for spin qubit application

First-principles calculations in combination with group theory analyses were employed to study the spin-polarized electronic structures of C_BV_N centers consisting of a nitrogen vacancy and a substitutional carbon atom in hexagonal boron nitride (h-BN) monolayer with different charge states. It is clarified that the paramagnetic neutral C_BV_N center is stable in the n-type h-BN monolayer. The neutral defect center possesses a triplet (S = 1) ground state and with two spin-conserved optical vertical transition. Its spin coherence time is estimated to be 3.9 ms at T = 0 K by a simple scheme combining the mean-field theory and the first-principles calculations. The results indicate that the neutral C_BV_N center is very suitable for achieving spin qubit.