Strong Electric-dipole-enabled transitions in the excited state of the Nitrogen Vacancy center in diamond

The negative charge state of the NV center is a quantum sensor mostly known for its remarkable ability to sense magnetic fields at the nanoscale. But its excited states also possess strong electric dipoles, which can serve as a resource for entanglement, emission tuning, or electric field sensing. Here, we use resonant laser excitation to expose strong electric transitions in the excited state (ES) orbitals of the negatively charged nitrogen vacancy center in diamond [1]. By applying microwave electric fields, we perform strong Rabi driving between ES orbitals, and show that the dressed states can be tuned in frequency and are protected against fluctuations of the transverse electric field [1,2]. Additionally and in contrast with previous results, we observe sharp microwave resonances between magnetic states of the ES orbitals, and find that they are broadened due to simultaneous electric dipole driving. All in all, these results portend fast electrical control of NV excited state orbitals without the need for ultra-fast optical pulses [2] or resonators [3], which could be applied to create electric entanglement of proximal NVs, or to study other electric-active defects in bulk diamond and diamond interfaces.

[1] T. Delord, R. Monge, G. Lopez-Morales, O. Bach, C. E. Dreyer, J. Flick, and C. A. Meriles, _Probing Electric-Dipole-Enabled Transitions in the Excited State of the Nitrogen-Vacancy Center in Diamond_, arXiv:2405.16280.

[2] L. C. Bassett, F. J. Heremans, D. J. Christle, C. G. Yale, G. Burkard, B. B. Buckley, and D. D. Awschalom, Ultrafast optical control of orbital and spin dynamics in a solid-state defect, Science **345**, 1333 (2014).

[3] B. A. McCullian, V. Sharma, H. Y. Chen, J. C. Crossman, E. J. Mueller, and G. D. Fuchs, Coherent Acoustic Control of Defect Orbital States in the Strong-Driving Limit, PRX Quantum 5, 030336 (2024).