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

TL;DR

This paper demonstrates how one- and two-phonon interference can be used to control phonon squeezing and correlation in ZnTe crystals, revealing a trade-off between these quantum properties through experimental manipulation.

Contribution

It introduces a method to manipulate phonon squeezing and correlation via interference effects in a specific crystal, advancing quantum control of phononic states.

Findings

Controlled phonon squeezing and correlation through interference.

Experimental demonstration of manipulation in ZnTe crystals.

Trade-off observed between phonon correlation and squeezing.

Abstract

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 acoustic 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 two-phonon bound (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 demonstrate experimentally that when two biphonon ensembles are temporally and spatially overlapped, the strength of phonon squeezing and correlation can be controlled. However, due to the complementarity of one- and two-phonon interference a larger correlation comes at the expense of a reduced squeezing.