Nature 478, 89–92 (2011)

Credit: © 2011 NPG

The field of optomechanics, in which light is used to influence the behaviour of miniature mechanical devices, has taken a significant step forward with the recent news that researchers have successfully laser-cooled a nanomechanical oscillator to its quantum ground state. Although physicists are keen to explore the quantum behaviour of a mechanical oscillator, the effects are hidden from view at normal temperatures and can only be accessed at very low temperatures, which are difficult to reach. A team from Caltech in the USA and the University of Vienna in Austria have now used photonics to reach the quantum regime in an experiment that operates at an environmental temperature of 20 K — around 1,000 times higher than previous experiments. Jasper Chan and colleagues fabricated a silicon nanobeam cavity and placed it into a helium cryostat at a temperature of 20 K. They then fed light from a tunable laser into the nanobeam via a tapered fibre nanoprobe. By tuning the laser wavelength to a slightly longer frequency than the resonance of the nanobeam optical cavity, the light can be used to perform optically induced damping of the mechanical motion, thereby cooling the oscillator to its quantum ground state. The researchers say that experiments for preparing and measuring the non-classical quantum states of the mechanical system are now within reach.