Arbitrary manipulation of nuclear spins in hexagonal boron nitride

Due to its localized nature and controllability, the negatively charged boron vacancy centers V$_B^-$ in hexagonal boron nitride (hBN) are a promising spin platform for accessing its neighboring nuclei with potential for performing quantum computational tasks. However, the methods of utilizing and manipulating the nuclear spins are still lacking. In this work, we propose a protocol for the preparation of single- and multi-qubit gates on the nuclear spins, utilizing the electron spin as an auxiliary qubit. By applying a background magnetic field and a multi-tone continuous drive, we show that the electron spin coupling to the nuclei can be efficiently engineered. This allows for suppressing the undesired electron-nuclear interactions through the Hahn echo pulse sequence. The target gates are then implemented by employing proper RF drives. Our numerical results for realistic parameters show gate fidelities as high as 99\% for single-qubit and 95\% for multi-qubit gates. With the gate execution durations being less than 300 ns, our protocol evades electron spin decoherence effects. Therefore, our scheme sets the stage for the practical application of V_B^- in hBN for quantum computation purposes.