Hyma Harish Vallabhapurapu

Nuclear spins are known to present a robust platform for implementation of spin-qubits for applications in quantum information processing and memory nodes for quantum communication. However, direct control of the nuclear spins using NMR techniques results in drastically slow kilohertz rate gate operation times compared to the electron spin, simply due to the generally-low gyromagnetic ratios of nuclear spins. Indirect control techniques have been developed in the past [1] to address this issue in color centers in diamond such as the Nitrogen-Vacancy center [2,3] and the Silicon-Vacancy center [4,5] (albeit on randomly occurring nearest neighbor $^{13}$C spins) by taking advantage of the ease of control of the electron spin to actuate on the nuclear spin through the anisotropic hyperfine coupling. Silicon-Vacancy centers in diamond have recently proven to be promising optically addressed spin-qubit platforms at low temperatures [6]. However, indirect control methods have not yet been shown to be feasible on the host nuclear spin simply due to the dominant isotropic nature of the hyperfine coupling. In this work [7] we show that using timed pi-rotations on the electron spin, megahertz rate coherent indirect control of the $^{29}$Si nuclear spin is feasible when considering the effect of the intrinsic Spin-Orbit coupling and relevant parameters in the Hamiltonian such as the applied magnetic field and strain.

References
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[2] J. Zhang, S. S. Hegde, and D. Suter, Improved Indirect Control of Nuclear Spins in Diamond N-V Centers, Phys. Rev. Applied 12, 064047 (2019).
[3] E. Takou, E. Barnes, and S. E. Economou, Multipartite electronnuclear gates in defect systems through dynamical decoupling sequences, arXiv:2203.09459.
[4] C. T. Nguyen, D. D. Sukachev, M. K. Bhaskar, B. Machielse, D. S. Levonian, E. N. Knall, P. Stroganov, R. Riedinger, H. Park, M. Loncar, and M. D. Lukin, Quantum Network Nodes Based on Diamond Qubits with an Efficient Nanophotonic Interface, Phys. Rev. Lett. 123, 183602 (2019).
[5] S. Maity, B. Pingault, G. Joe, M. Chalupnik, D. Assumpção, E. Cornell, L. Shao, and M. Loncar, Mechanical Control of a Single Nuclear Spin, Phys. Rev. X 12, 011056 (2022).
[6] Bhaskar, M.K., Riedinger, R., Machielse, B. et al. Experimental demonstration of memory-enhanced quantum communication. Nature 580, 60–64 (2020).
[7] H.H. Vallabhapurapu, C. Adambukulam, A. Saraiva, A. Laucht, Indirect Control of the 29SiV- nuclear spin in Diamond, Phys. Rev. B (Accepted 11 May 2022). arXiv:2203.10283