Ultralow-dissipation micro-oscillator for quantum optomechanics

Generating nonclassical states of light by optomechanical coupling depends critically on the mechanical and optical properties of micro-oscillators and on the minimization of thermal noise. We present an oscillating micromirror with a mechanical quality factor Q=2.6×10⁶ at cryogenic temperature and a finesse of 65 000, obtained thanks to an innovative approach to the design and the control of mechanical dissipation. We predict that, already at 4 K with an input laser power of 2 mW, the radiation-pressure quantum fluctuations become the main noise source, overcoming thermal noise. This feature makes our devices particularly suitable for the production of ponderomotive squeezing.