Self-cooling of a micro-mirror by radiation pressure
  We demonstrate passive feedback cooling of a mechanical resonator based on radiation pressure forces and assisted by photothermal forces in a high-finesse optical cavity. The resonator is a free-standing high-reflectance micro-mirror (of mass m=400ng and mechanical quality factor Q=10^4) that is used as back-mirror in a detuned Fabry-Perot cavity of optical finesse F=500. We observe an increased damping in the dynamics of the mechanical oscillator by a factor of 30 and a corresponding cooling of the oscillator modes below 10 K starting from room temperature. This effect is an important ingredient for recently proposed schemes to prepare quantum entanglement of macroscopic mechanical oscillators. 
S. Gigan, H. R. Boehm, M. Paternostro, F. Blaser, G. Langer, J. B.   Hertzberg, K. Schwab, D. Baeuerle, M. Aspelmeyer, A. Ze...