VACUUM SQUEEZING OF SOLIDS - MACROSCOPIC QUANTUM STATES DRIVEN BY LIGHT-PULSES

Femtosecond laser pulses and coherent two-phonon Raman scattering were used to excite KFaO(3) into a squeezed state, nearly periodic in time , in which the variance of the atomic displacements dips below the sta ndard quantum limit for half of a cycle. This nonclassical state invol ves a continuum of transverse acoustic modes that leads to oscillation s in the refractive index associated with the frequency of a van Hove singularity in the phonon density of states.