Observation of electromagnetically induced transparency in evanescent fields

TL;DR

This paper demonstrates electromagnetically-induced transparency in evanescent fields at a glass-rubidium interface, revealing a narrow spectral feature with potential for compact frequency references.

Contribution

It provides both experimental and theoretical insights into EIT in evanescent fields, highlighting the independence of peak width from interaction region thickness and suggesting applications in miniaturized frequency standards.

Findings

EIT observed as a sharp, non-Lorentzian peak with ~1 MHz width.

Peak width is unaffected by the interaction region thickness.

Wall collisions are identified as the primary decoherence source.

Abstract

We observe and investigate, both experimentally and theoretically, electromagnetically-induced transparency experienced by evanescent fields arising due to total internal reflection from an interface of glass and hot rubidium vapor. This phenomenon manifests itself as a non-Lorentzian peak in the reflectivity spectrum, which features a sharp cusp with a sub-natural width of about 1 MHz. The width of the peak is independent of the thickness of the interaction region, which indicates that the main source of decoherence is likely due to collisions with the cell walls rather than diffusion of atoms. With the inclusion of a coherence-preserving wall coating, this system could be used as an ultra-compact frequency reference.