Ultrahigh-Q mechanical oscillators through optical trapping
  Rapid advances are being made toward optically cooling a single mode of a micro-mechanical system to its quantum ground state and observing quantum behavior at macroscopic scales. Reaching this regime in room-temperature environments requires a stringent condition on the mechanical quality factor $Q_m$ and frequency $f_m$, $Q_{m}f_{m}{\gtrsim}k_{B}T_{{bath}}/h$, which so far has been marginally satisfied only in a small number of systems. Here we propose and analyze a new class of systems that should enable unprecedented $Q_{m}f_m$ values. The technique is based upon using optical forces to "trap" and stiffen the motion of a tethered mechanical structure, thereby freeing the resultant mechanical frequencies and decoherence rates from underlying material properties. 
D.E. Chang, K.-K. Ni, O. Painter, and H.J. Kimble
quant-ph