Acoustic Controlof Spin States in Diamond Nitrogen-VacancyCentres

We report acoustic control of spin resonance in nitrogen-vacancy (NV–) centers in diamond using low-frequency free-space sound waves. Acoustic excitation redistributes spin populations between the |+1⟩ and |−1⟩ states, producing an asymmetric, tunable double-dip ODMR spectrum without shifting resonance frequencies. This contrasts with conventional magnetic-field-induced splitting and reveals a previously unobserved mechanism for spin manipulation via strain-mediated acoustic coupling. Analytical modeling captures the essential features of the amplitude flipping and elucidates the underlying spin-strain interaction. Our findings establish a new degree of freedom for selective multimodal quantum sensing and open avenues for hybrid spin-mechanical quantum devices.