Quantum vacuum emission in a nonlinear optical medium illuminated by a strong laser pulse

TL;DR

This paper develops a quantum theory for light in nonlinear optical media with strong pulses, revealing vacuum emission phenomena analogous to Hawking radiation and showing that dispersive media can produce spontaneous emission even without horizons.

Contribution

It introduces a quantum framework incorporating dispersion effects in nonlinear media, highlighting vacuum emission mechanisms both with and without horizon analogs.

Findings

Spectrum of emitted particles resembles Hawking radiation near horizons

Vacuum emission occurs even without horizons due to dispersion

Dispersive properties significantly alter emission spectra

Abstract

A strong light pulse propagating in a nonlinear Kerr medium produces a change in the refractive index, which makes light travel at different speeds inside and outside the pulse. By tuning the pulse velocity, an analog black hole horizon can be obtained in a suitable frequency window. In this paper, we develop a quantum theory of light propagation for this system, including the frequency dispersion of the refractive index of the medium by coupling the electromagnetic field to matter polarization fields. In a configuration with a single black hole horizon, the spectrum of spontaneously emitted particles presents some similarities with Hawking radiation. Furthermore, even in horizonless systems spontaneous vacuum emission is still possible due to the dispersive nature of the medium, yet with dramatically different spectral properties.