Phonon Lasers

Amazing advancement this week in the area of producing phonon lasers. Two new papers published by two different groups have made significant progress in producing such a thing.

Despite all the similarities between photons and phonons, no phonon lasers have been developed up until now. The difficulty, ironically, can be traced to the same fact that makes phonon lasers so desirable [4]—the comparatively short wavelength of sound, which causes spontaneous emission processes to dominate over stimulated emission unless one modifies the density of phonon states by employing high-quality acoustic resonators.

You also can get the actual papers for free from that link.

Zz.