title: Photon number statistics uncover the fluctuations in non-equilibrium lattice dynamics.
abstract: Fluctuations of the atomic positions are at the core of a large class of unusual material properties ranging from quantum para-electricity to high temperature superconductivity. Their measurement in solids is the subject of an intense scientific debate focused on seeking a methodology capable of establishing a direct link between the variance of the atomic displacements and experimentally measurable observables. Here we address this issue by means of non-equilibrium optical experiments performed in shot-noise-limited regime. The variance of the time-dependent atomic positions and momenta is directly mapped into the quantum fluctuations of the photon number of the scattered probing light. A fully quantum description of the non-linear interaction between photonic and phononic fields is benchmarked by unveiling the squeezing of thermal phonons in α-quartz.
authors.affiliation: Dipartimento di Fisica, Università di Trieste, Via Valerio 2 Trieste 34127, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Esposito
authors.affiliation: Dipartimento di Fisica, Università di Trieste, Via Valerio 2 Trieste 34127, Italy.|Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste 34014, Italy.
authors.forename: Kelvin
authors.initials: K
authors.lastname: Titimbo
authors.affiliation: Dipartimento di Fisica, Università di Trieste, Via Valerio 2 Trieste 34127, Italy.|Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste 34014, Italy.
authors.forename: Klaus
authors.initials: K
authors.lastname: Zimmermann
authors.affiliation: Dipartimento di Fisica, Università di Trieste, Via Valerio 2 Trieste 34127, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Giusti
authors.affiliation: Dipartimento di Fisica, Università di Trieste, Via Valerio 2 Trieste 34127, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Randi
authors.affiliation: Ecole polytechnique, ENSTA ParisTech, CNRS, Université Paris-Saclay, 828 boulevard des Maréchaux, Palaiseau 91762, France.
authors.forename: Davide
authors.initials: D
authors.lastname: Boschetto
authors.affiliation: Dipartimento di Fisica, Università di Trieste, Via Valerio 2 Trieste 34127, Italy.|Sincrotrone Trieste S.C.p.A., Basovizza 34127, Italy.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Parmigiani
authors.affiliation: Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste 34014, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Floreanini
authors.affiliation: Dipartimento di Fisica, Università di Trieste, Via Valerio 2 Trieste 34127, Italy.|Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste 34014, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Benatti
authors.affiliation: Dipartimento di Fisica, Università di Trieste, Via Valerio 2 Trieste 34127, Italy.|Sincrotrone Trieste S.C.p.A., Basovizza 34127, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Fausti