Controlling phonon squeezing and correlation via one- and two-phonon interference

When ultrafast laser pulse strikes the crystal with a van Hove singularity in the phonon density of states, it can create a pair of anti-correlated in wave-vector phonons. As a result, the atomic fluctuations in either position or momentum become squeezed in such a way that their size might fall below the vacuum level. The ultrafast pulses can also generate a biphonon state in which the constituent phonons are correlated and/or entangled. Here we show that via the interplay between one- and two-phonon interference the bound and squeezed two-phonon state in (110) oriented ZnTe single crystal can be manipulated.

► We use a pair of ultrafast laser pulses to manipulate squeezing and correlation of biphonons in ZnTe.
► We demonstrate that the strength of phonon squeezing and correlation can be controlled.
► We observe that a larger correlation comes at expense of a reduced squeezing.