Physics

Cooler Vibrations

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Science  27 Jul 2007:
Vol. 317, Issue 5837, pp. 429
DOI: 10.1126/science.317.5837.429a

Optical back action can be used to cool micrometer-sized objects such as microresonators and micromirrors to temperatures as low as 1 K. The motivation for such cooling is to be able to access the quantum mechanical oscillations of the thermal vibrations and to use the measurement of these ultrasmall vibrations as exquisite motion sensors for detecting gravity waves as well as for probing possible quantum-mechanical effects in macroscopic systems. Poggio et al. show that the cooling can be taken a step further by optimized coupling of an optical cooling setup with the electromechanical motion of a single-crystal silicon cantilever. In their system, 100 nW of laser light is focused onto the paddle of the mass-loaded cantilever, the motion of which is detected in an arm of an interferometer. This interferometric signal is then fed back to induce a piezoelectric mechanical response, resulting in cold damping of the cantilever motion. The net effect is a lowering of the cantilever temperature below 5 mK. — ISO

Phys. Rev. Lett. 99, 017201 (2007).

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