Goos-H\"anchen and Imbert-Fedorov shifts from a quantum-mechanical perspective

TL;DR

This paper presents a quantum-mechanical formalism to analyze Goos-H"anchen and Imbert-Fedorov shifts in reflected light beams, revealing new insights into their separation, dependence on orbital angular momentum, and enhancement via weak measurements.

Contribution

It introduces a quantum-mechanical approach to separate and analyze GH and IF shifts, including OAM effects and weak measurement enhancement, connecting theory with recent experiments.

Findings

Spatial shift separates into OAM-independent and OAM-induced parts

Angular shift is proportional to the beam's angular spread

Weak measurements can enhance beam shifts

Abstract

We study the classical optics effects known as Goos-H\"anchen (GH) and Imbert-Fedorov (IF) shifts, occurring when reflecting a bounded light beam from a planar surface, by using a quantum-mechanical formalism. This new approach allows us to naturally separate the spatial shift into two parts, one independent on orbital angular momentum (OAM) and the other one showing OAM-induced spatial-vs-angular shift mixing. In addition, within this quantum-mechanical-like formalism, it becomes apparent that the angular shift is proportional to the beams angular spread, namely to the variance of the transverse components of the wave vector. Moreover, we extent our treatment to the enhancement of beam shifts via weak measurements and relate our results to recent experiments.