Phonon squeezing

Photon squeezing has been the subject of intense interest in the field of quantum optics, since it serves as a unique demonstration of the quantum nature of light. On a practical level, squeezing offers opportunities to make interferometric measurements much more precise than would normally be allowed by quantum uncertainty limits. In principle, the physics of squeezing may be applied to many different types of bosons. Our work demonstrates phonon squeezing by using femtosecond laser excitation of bismuth to create squeezed phonon states and then femtosecond x-ray diffraction to watch how the atomic position variance in the crystal evolves in time.