Photonics.com reports that several groups have developed methods of cooling mirrors using not much more than beams from lasers. The research is aimed at revealing quantum effects in our macroscopic world.
Cooling occurs when photons bounce off a springlike structure with a natural resonant frequency. If a laser is off that frequency, the light acts like an ultracold viscous fluid, damping movement and, therefore, cooling the structure. The key to achieving the lowest possible temperature is to have a low-mass, highly reflective mirror mounted on a springy structure of high mechanical quality.