S. Seidelin, Y. Le Coq and K. Mølmer  

Phys. Rev. A 100, 013828 – Published 16 July 2019

We consider an optical probe that interacts with an ensemble of rare-earth ions doping a material in the shape of a cantilever. By optical spectral hole burning, the inhomogeneously broadened transition in the ions is prepared to transmit the probe field within a narrow window, but bending of the cantilever causes strain in the material which shifts the ion resonances. By interacting dispersively with a detuned laser, and making a feedback on the laser intensity, the resonator can be cooled down close to the quantum groundstate.