Spatial Kramers-Kronig relation and unidirectional light reflection induced by Rydberg dipole-dipole interactions

TL;DR

This paper introduces a spatial Kramers-Kronig relation framework using Rydberg dipole-dipole interactions, enabling tunable unidirectional light reflection and enhanced nonzero reflectivity through Bragg scattering.

Contribution

It presents a novel method to realize a spatial KK relation with unidirectional reflection using Rydberg atoms and incorporates Bragg scattering for improved reflectivity.

Findings

Achieves dynamically tunable asymmetric and unidirectional reflection.

Demonstrates enhancement of reflectivity via Bragg scattering.

Maps KK relation from frequency to space domain using Rydberg interactions.

Abstract

Kramers-Kronig (KK) relation between the dispersion and absorption responses of a signal field can be mapped from the frequency domain into the space domain via the dipole-dipole interactions between a homogeneous sample of target atoms and a control atom. This is achieved by establishing an effective two-level configuration for the three-level target atoms in the single-photon far-detuned driving regime while maintaining a high Rydberg excitation for the three-level control atom in the single-photon resonant driving regime. We find in particular that it is viable to realize a dynamically tunable spatial KK relation supporting asymmetric and even unidirectional reflection for appropriate signal frequencies in a controlled range. Taking a periodic lattice of target atoms instead, multiple Bragg scattering can be further incorporated into spatial KK relation to largely enhance the nonzero reflectivity yet without breaking the asymmetric or unidirectional reflection.