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 $f_m$, $Q_{m}f_{m} \ga k_{B}T_{\footnotesize\textrm{bath}}/h$, 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 [1-3]. The technique is based upon using optical forces to ``trap'' and stiffen the motion of a tethered mechanical structure [3], thereby freeing the resultant mechanical frequencies and decoherence rates from underlying material properties. We have lithographically fabricated a diverse set of planar structures in Silicon Nitride, made measurements of their optical and mechanical properties, and compared these results to numerical models by finite element analysis.\\[4pt]This work has been carried out in collaboration with D. E. Chang, K.-K. Ni, R. Norte, O. J. Painter, and D. J. Wilson. \\[4pt] [1] D. E. Chang, C. A. Regal, S. B. Papp, D. J. Wilson, J. Ye, O. Painter, H. J. Kimble, and P. Zoller, Proceedings of the National Academy of Sciences (PNAS) \textbf{107}, 1005 (2010); available at www.pnas.org/cgi/doi/10.1073/pnas.0912969107 (2009). \\[0pt] [2] O. Romero-Isart, M. L. Juan, R. Quidant, and J. I. Cirac, New J. Phys. \textbf{12}, 033015 (2010). \\[0pt] [3] D. E. Chang, K.-K. Ni, O. J. Painter, and H.J. Kimble, arXiv:1101.0146v1 [quant-ph] 30 Dec 2010.