Observability of the superkick effect within a quantum-field-theoretical approach

An atom placed in an optical vortex close to the axis may, upon absorbing a photon, acquire a transverse momentum much larger than the transverse momentum of any plane-wave component of the vortex light field. This surprising phenomenon dubbed superkick has been clarified previously in terms of the atom wave-packet evolution in the field of an optical vortex treated classically. Here, we study this effect within the quantum field theoretical (QFT) framework. We consider collision of a Bessel twisted wave with a compact Gaussian beam focused to a small focal spot sigma located at distance b from the twisted beam axis. Through a qualitative discussion supported by exact analytical and numerical calculations, we recover the superkick phenomenon for sigma << b and explore its limits when sigma becomes comparable to b. On the way to the final result within the QFT treatment, we encountered and resolved apparent paradoxes related to subtle issues of the formalism. These results open a way to a detailed QFT exploration of other superkick-related effects recently suggested to exist in high-energy collisions.

Automated summary

An atom in an optical vortex can acquire a larger transverse momentum than any plane-wave component of the vortex light field after absorbing a photon, a phenomenon called "superkick". This study explores the superkick effect using quantum field theory framework, encountering and resolving apparent paradoxes along the way. The results provide insights for further exploration of superkick-related effects in high-energy collisions.