Enhancement of mechanical Q-factors by optical trapping*

The quality factor (Q) of a mechanical resonator is an important figure of merit for observing quantum behavior. We demonstrate a technique to push the quality factor of a micro-mechanical resonator beyond conventional material and fabrication limits by using an optical lattice to trap a particular motional mode. A majority of the resonator's energy is stored in the lossless optical potential, thereby strongly diluting the effect of material dissipation. The pendulum-like mechanical resonator consists of a suspended 10 $\mu$m diameter, 140 nm thick Si0$_2$ disk attached to the substrate by a single thin tether. The disk is trapped at the intensity maximum of an optical lattice, and we observe a frequency increase of the center of mass from 6.2 KHz to 145 KHz with a 50 fold Q increase to a final value of $5.8\times10^{5}$. This technique shows a strong potential in bringing other micro-mechanical resonators, such as SiN membranes, into a low-loss regime where observation of quantum behavior in macroscopic devices at room temperature becomes possible.