Spin-polarization of V _GaO _N center in GaN and its application in spin qubit

V _GaO _N center in cubic gallium nitride is a defect complex composing of a substitutional oxygen atom at nitrogen site (O _N) and an adjacent gallium vacancy (V _Ga). Based on first-principles calculations, we predicted that this V _GaO _N center has much in common with the famous nitrogen-vacancy center in diamond, but the excitation energy is very low. The electron spin-polarization of the centers can be tuned by changing the charge states. The neutral O _NV _Ga center has the v ↓ and e _xy ↓ states being well isolated from the bulk bands with appropriate spacing which are suitable for achieving spin qubit operation with low excitation energy.