Scientists examine possibility of a phonon laser, or 'phaser'

Scientists examine possibility of a phonon laser, or 'phaser': "In the new method, the gas is confined in a magneto-optical trap. Three physical processes are used to create the phonon laser instability. First, a red-detuned laser beam cools the atomic gas to ultra-cold temperatures. Then, a blue-detuned laser pumps the ultra-cold atomic gas to create a population inversion, which is also a standard requirement for optical lasers. Finally, the atoms produce a coherent emission of phonons and then decay into a lower kinetic energy state. The scientists note that the resulting acoustic oscillations can then be coupled to the outside world by mechanical or electromagnetic means, where they could be used to provide a source of coherent acoustic radiation."