Optically tunable dynamics of nano-mechanica systems
Final Report Abstract
How to easily excite nanomechanical elements and control their motion was and still is a challenging problem. Although on a micromechanical scale we have started performing experiments on tuning the mechanics of microlevers with light and even a light-induced cooling of the microlever has been achieved. This opened new routes for driving and controlling nanomechanical systems by optical means. Mirrors confine light, and light exerts pressure on mirrors. The combination of these effects can be exploited to cool tiny, flexible minors to low temperatures purely through the influence of incident light. In these experiments, the degree of cooling achieved so far is limited by the heating that results from vibrations ofthe minor's flexible attachments, and most probably from residual optical absorption by the minor. To observe the promised quantum-mechanical effects, cooling to just a few millikelvin is needed. That could require the use of more sophisticated nanofabrication techniques to produce mechanical oscillators of lower mass that are more easily damped, and cavities of increased optical quality. We have also employed optomechanical coupling to study the interaction between photons stored in a high finesse Fabry-Perot cavity and a mechanical nanoresonator. A carbon-based nanorod is placed in a highfinessefiber-integratedoptical cavity of micron-size mode volume resonantly probed by a laser. The vibrational motion ofthe nanorod modulates the cavity optical transmission and is this way efficiently detected. Our studies represent a first step towards optomechanical systems at the nanoscale, where confined photons and nanomechanical resonators can interact strongly enough to modify each other's dynamics. Among the prizes for such endeavours could be the chance to study quantum superpositions of a photon and a macroscopic mechanical oscillator. That in tum might find practical use in ultra-precise methods for displacement sensing and for measuring the mass of single atoms and molecules. The road to that destination is a long one; but it is at least now well signposted.
Publications
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Cavity cooling of a microlever, NATURE 432 1002 (2004)
C. Höhberger Metzger and K. Karrai
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A cooling light breeze, News and Views Article in Nature 444, 41 (2006)
Khaled Karrai
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Cavity cooling of a nanomechanical resonator by light scattering, (2007)
I. Favero, K. Karrai
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Optical cooling of a micromirror of wavelength size, APL 90, 041101 (2007)
I. Favero, C. Metzger, S. Camerer, D. König, H. Lorenz, J. P. Kotthaus, and K. Karrai
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Self-induced oscillations in an optomechnanical system, (2007)
M. Ludwig, C. Neuenhahn, C. Metzger, A. Ortlieb, I. Favero, K. Karrai, and F. Marquardt
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Doppler Optomechanics of a Photonic Crystal, Phys. Rev. Lett, 100 240801 (2008)
K. Karrai, L Favero, C. Metzger
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Optical self cooling of a deformable Fabry-Perot cavity in the classical limit, Phys. Rev. B 78 035309 (2008)
Constanze Metzger, Ivan Favero, Alexander Ortlieb, and Khaled Karrai
