Photon-pair generation in random nonlinear layered structures

TL;DR

This paper explores how random nonlinear layered structures can generate narrowband, nearly unentangled photon pairs with controllable spectral properties, useful for quantum optics applications.

Contribution

It demonstrates the use of random 1D nonlinear layered structures to produce narrow spectral bandwidth photon pairs with tunable entanglement properties.

Findings

Photon pairs with extremely narrow spectral bandwidths are achievable.

Indistinguishable photons are nearly unentangled in these structures.

Superposition of photon pairs at different emission angles enables frequency coincidence.

Abstract

Nonlinearity and sharp transmission spectra of random 1D nonlinear layered structures are combined together to produce photon pairs with extremely narrow spectral bandwidths. Indistinguishable photons in a pair are nearly unentangled. Also two-photon states with coincident frequencies can be conveniently generated in these structures if photon pairs generated into a certain range of emission angles are superposed. If two photons are emitted into two different resonant peaks, the ratio of their spectral bandwidths may differ considerably from one and two photons remain nearly unentangled.