Identification of the phosphorus-doping defect in MgS as a potential qubit

The P_S defect is obtained by replacing one S atom with one P atom in the wide-bandgap semiconductor MgS. Based on first-principles calculations, the formation energy, defect levels, and electronic structure of the P_S defect in different charge states are evaluated. We predict that the neutral P_S⁰ and positively charged P_S⁺¹ are the plausible qubit candidates for the construction of quantum systems, since they maintain the spin conservation during optical excited transition. The zero-phonon lines at the P_S⁰ and P_S⁺¹ defects are 0.43 eV and 0.21 eV, respectively, which fall in the infrared band. In addition, the zero-field splitting parameter D of the P_S⁺¹ with spin-triplet is 2920 MHz, which is in the range of microwave, showing that the P_S⁺¹ defect can be manipulated by microwave. Finally, the principal values of the hyperfine tensor are examined, it is found that they decay exponentially with the distance from the defect site.