Quantum Mechanical Vibrations Directly ObservedCategory: Science & Technology
Posted: August 24, 2012 06:21PM
Light is kind of funny because while photons are massless, they can still impart momentum onto an object. This is what allows solar sails to work, which catch photons like a breeze to propel a spacecraft. Researchers at Berkeley Lab decided to study this on the quantum scale by using an optical cavity and an ultrasensitive force sensor.
Within an optical cavity, light will bounce back and forth at specific resonant frequencies, similar to how a string vibrates on an instrument. The researchers placed an atomic-sized mechanical resonator inside of the cavity, so as the light hits it, it will vibrate back and forth due to the light's momentum. The momentum of the light fluctuates though, due to the position of the resonator and quantum mechanical effects. By applying a low powered laser to the optic cavity, and cutting it off, the researchers were able to do something no one has previously accomplished, which was to measure the fluctuations brought on just by quantum mechanical effects.
Carefully observing the light in the cavity, the researchers found the light was amplified and squeezed, which has been predicted by theory but never observed before. This squeezing could prove very useful for gravitational wave detectors in the future, which try to measure ripples in the curvature of spacetime itself. However this setup itself is quite intriguing as it could be adapted for quantum information processing.