Description:
Very regular clocks are essential in our everyday lives. They enable us to navigate, from the marine chronometers used to determine longitude, to GPS. Stable clocks power the internet, defining the speed with which information can be sent and received.
If your timepiece is very precise, it is easy to detect even small changes to its regularity. By measuring the motion of a physical object which is keeping time, such as the pendulum of a grandfather clock, and comparing it to an electronic reference, then we can detect disturbances, such as vibrations of the case.
An amazingly stable, material hand for an electronic clock has been created through the rotations of a micrometre sized silicon cylinder, levitated by light. The rotor is kicked with pulses of polarized light, causing it to spin one million times a second, without any loss of stability. In tests it lost only one-millionth of a second over four days.
Other such tiny mechanical devices are limited in precision through contact with their environment, but when levitated the nano-rotor remains extremely stable for very long times.