First-principles Studies of Strongly Correlated States in Defect Spin Qubits in Diamond*

Spin defects in semiconductors, for example nitrogen-vacancy center in diamond, are promising spin qubits to build scalable quantum technologies, including quantum sensing and communication technologies. Despite ongoing efforts in the literature, predicting the singlet states of spin defects is still a challenging task, due to their strongly correlated nature. Using a recently developed quantum embedding theory [1], we present first-principles calculations of strongly correlated states of spin defects in diamond [2]. Within this theory, effective Hamiltonians are constructed, which can be solved by classical and quantum computers; the latter promise a much more favorable scaling as a function of system size than the former. In particular, we report a study of the neutral group-IV vacancy complexes in diamond, and we discuss their strongly correlated excited states. Our results provide valuable predictions for experiments aimed at optical manipulation of these defects.

[1] He Ma, Marco Govoni and Giulia Galli. npj Comput Mater 6, 85 (2020).
[2] He Ma, Nan Sheng, Marco Govoni, and Giulia Galli. Phys. Chem. Chem. Phys. (2020).