  We present a general method to realize resonant coupling between spins even
though their energies are of different scales. Applying the method to the
electron and nuclear spin systems such as a nitrogen-vacancy (NV) center with
its nearby nuclei, we show that a specific dynamical switching of the electron
spin Rabi frequency achieves efficient electron-nuclear coupling, providing a
much stronger quantum sensing signal and dynamic nuclear polarization than
previous methods. This protocol has applications in high-field nanoscale
nuclear magnetic resonances as well as low-power quantum control of nuclear
spins.
