In our modern information age, nano- and micromechanical oscillators are indispensable technologies that enable navigation, timing, motional sensing and wireless communication. They are used in particular for radio frequency filtering as well as for measuring rotation and acceleration and are employed commercially in cell phones, automobiles and airplanes.
The quality factor of mechanical oscillators can be extremely high, even in the gigahertz range, and in general, they have unique advantages over their electronic counterparts.
In the past decade, a technological and scientific revolution has occurred with respect to the efficient, coherent operation of such mechanical devices: In analogy to the previous quantum control of atoms, ions, and molecules and, later, electrical circuits, nano- and micromechanical devices can now be interrogated and controlled at the quantum level using optical fields, thus establishing the field of cavity optomechanics.
By employing optical resonators that greatly enhance otherwise weak radiation pressure, the resonant build-up of laser light in an optical cavity gives rise to parametric coupling of the optical and mechanical degrees of freedom, enabling cooling, amplification, and unprecedentedly sensitive detection of mechanical motion. The latter includes microwave circuits with vibrating capacitive elements.