Spectra of ultrabroadband squeezed pulses and the finite-time Unruh-Davies effect

TL;DR

This paper investigates the spectral properties of ultrashort quantum pulses generated in nonlinear crystals, relating their spectra to the Unruh-Davies effect and describing their electric field variance in time.

Contribution

It introduces a continuous multimode squeezing operator for subcycle pulses and connects the spectra of emitted quantum radiation to finite-time Unruh-Davies experiments.

Findings

Ultrabroadband spectra of quantum radiation are derived perturbatively.

Spectra are related to finite-time acceleration in Unruh-Davies scenarios.

Time-domain electric field variance behavior is characterized.

Abstract

We study spectral properties of quantum radiation of ultimately short duration. In particular, we introduce a continuous multimode squeezing operator for the description of subcycle pulses of entangled photons generated by a coherent-field driving in a thin nonlinear crystal with second order susceptibility. We find the ultrabroadband spectra of the emitted quantum radiation perturbatively in the strength of the driving field. These spectra can be related to the spectra expected in an Unruh-Davies experiment with a finite time of acceleration. In the time domain, we describe the corresponding behavior of the normally ordered electric field variance.