Photon Squeezing in Photonic Time Crystals

TL;DR

This paper develops a quantum theory for photon pair generation in photonic time crystals, revealing how momentum bandgaps lead to exponential enhancement of quantum effects like vacuum amplification and squeezing.

Contribution

It introduces a Hermitian framework linking classical reflectivity and quantum pair generation in photonic time crystals, a novel approach in the field.

Findings

Momentum bandgaps cause exponential enhancement of pair generation.

A direct relation between reflectivity and squeezing parameter is established.

Quantum effects are characterized within an Hermitian theoretical framework.

Abstract

Time-varying media offer a platform to realize novel and exotic wave effects, including photonic time crystals characterized by momentum band gaps with exponential wave amplification. Here we focus on the quantum electrodynamical properties of time-varying media, in particular vacuum amplification and squeezing. For that purpose, we present a theory of photon pair generation in photonic time crystals that unveils the link between the classical and quantum electrodynamical properties of these systems, that is, a direct relation between reflectivity and pair generation through the squeezing parameter. By working within an Hermitian framework, we are able to characterize quantum pair generation processes in photonic time crystals, showing how momentum bandgaps result in a non-resonant exponential enhancement of dynamical Casimir processes.