Controlling X-ray emission with dispersion-engineered surface plasmon polaritons

We propose controlling the angular and spectral distribution of hard x-ray emission by entangling x-ray photons with ultraviolet surface plasmon polaritons (SPPs) whose dispersion is engineered by a metal-dielectric multilayer on a nonlinear crystal. Spontaneous parametric down-conversion of an x-ray pump produces a hard x-ray signal photon correlated with an ultraviolet SPP mode near its resonance. Engineering the SPPs dispersion reshapes the phase-matching landscape and imprints tunable angular-spectral structure on the emitted x-ray photons. The scheme enables compact, designable control of x-ray emission and extends surface-plasmon-assisted nonlinear and quantum x-ray optics.

💡 Research Summary

This paper presents a novel scheme for exerting designable control over the angular and spectral distribution of hard x-ray emission. The core idea leverages quantum entanglement between x-ray photons and ultraviolet surface plasmon polaritons (SPPs), where the dispersion of the SPPs is engineered using a metal-dielectric multilayer structure deposited on a nonlinear crystal.

The challenge in controlling hard x-rays stems from their high photon energy and momentum, which lead to weak coupling with valence electrons and refractive indices near unity in most materials, severely limiting conventional manipulation techniques. The authors build upon their previous experimental demonstration