Weak Measurements of Light Chirality with a Plasmonic Slit

TL;DR

This paper demonstrates how a plasmonic slit can be used as a sensitive platform for weak measurements of light's chirality, combining quantum weak measurement principles with plasmonic and near-field techniques.

Contribution

It introduces a novel experimental setup that uses a plasmonic slit for weak measurements of light helicity, integrating quantum measurement concepts with plasmonic systems.

Findings

Observation of the plasmonic spin Hall effect in coordinate and momentum spaces

Detection of real and imaginary weak values of light helicity

High sensitivity to incident light polarization

Abstract

We examine, both experimentally and theoretically, an interaction of tightly focused polarized light with a slit on a metal surface supporting plasmon-polariton modes. Remarkably, this simple system can be highly sensitive to the polarization of the incident light and offers a perfect quantum-weak-measurement tool with a built-in post-selection in the plasmon-polariton mode. We observe the plasmonic spin Hall effect in both coordinate and momentum spaces which is interpreted as weak measurements of the helicity of light with real and imaginary weak values determined by the input polarization. Our experiment combines advantages of (i) quantum weak measurements, (ii) near-field plasmonic systems, and (iii) high-numerical aperture microscopy in employing spin-orbit interaction of light and probing light chirality.