Mechanical sensing via a driven spin-mechanical system*

Solid-state spins such as diamond nitrogen vacancy (NV) centers have been widely used as quantum sensors for electric and magnetic fields, strain, and temperature via changes in the spin resonance. Here, we report the experimental demonstration of a mechanical sensing approach that exploits the interaction between a spin and a mechanical oscillator. In this experiment, a NV center is coupled to a high Q-factor diamond nanomechanical oscillator. The orbital states of the NV center are highly sensitive to crystal strain and can thus strongly couple to the mechanical oscillator. As a result, the driving of the mechanical oscillator near resonance by an external force can lead to a large sideband splitting in the dipole or spin transitions of the NV center. Our experimental studies show that this sideband splitting can be highly sensitive to changes as small as 0.1 Hz in the mechanical resonance frequency. The driven spin-mechanical system thus provides a platform for sensing or probing processes that can affect the resonance frequency of the mechanical oscillator.