Computational identification of defect qubits in transition metal dichalcogenide WSe₂

Nitrogen-vacancy (NV) center in diamond serves as a leading solid-state qubit system due to its fidelity of manipulation at room temperature, while the search for novel solid-state systems with NV-like defects is highly desirable for the future development of solid-state quantum technologies. Two-dimensional solid-state systems are superior platforms to implement controlled manipulation of qubits. Our computational studies focus on point defects in WSe₂ as one of the well-known compounds in the family of transition metal dichalcogenides (TMDs). First-principle calculations based on density functional theory are adopted to study the formation energetics and electronic properties of point defects including intrinsic defects such as V_W and Se antisite (W_Se), and extrinsic defects such as V_W-N_Se, V_W-P_Se, and V_W-As_Se. Our calculations show that both intrinsic and extrinsic defects can exhibit high magnetic moments and triplet ground states, which offer a set of defect candidates as qubits in this 2D TMD system. In addition, optical transition paths between ground and excited states will be discussed, which provide potential optical signatures for experimental verification.