Volume 81, Number 5, March 2008
Article Number 54003
Number of page(s) 5
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
Published online 12 February 2008
EPL, 81 (2008) 54003
DOI: 10.1209/0295-5075/81/54003

Radiation-pressure self-cooling of a micromirror in a cryogenic environment

S. Gröblacher1, S. Gigan1, H. R. Böhm1, 2, A. Zeilinger1, 2 and M. Aspelmeyer1

1  Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences Boltzmanngasse 3, A-1090 Vienna, Austria
2  Faculty of Physics, University of Vienna - Boltzmanngasse 5, A-1090 Vienna, Austria

received 16 November 2007; accepted in final form 10 January 2008; published March 2008
published online 12 February 2008

We demonstrate radiation-pressure cavity-cooling of a mechanical mode of a micromirror starting from cryogenic temperatures. To achieve that, a high-finesse Fabry-Pérot cavity (F$\approx$2200) was actively stabilized inside a continuous-flow 4He cryostat. We observed optical cooling of the fundamental mode of a 50 $\mu$m$\times$ 50 $\mu$m $\times$ 5.4 $\mu$m singly clamped micromirror at $\omega _{m}$ = 3.5 MHz from 35 K to approximately 290 mK. This corresponds to a thermal occupation factor of $\langle n\rangle \approx$ 1$\times$104. The cooling performance is only limited by the mechanical quality and by the optical finesse of the system. Heating effects, e.g. due to absorption of photons in the micromirror, could not be observed. These results represent a next step towards cavity-cooling a mechanical oscillator into its quantum ground state.

42.50.-p - Quantum optics.
07.10.Cm - Micromechanical devices and systems.
42.50.Wk - Mechanical effects of light on material media, microstructures and particles.

© EPLA 2008