Observation of Extra Photon Recoil in a Distorted Optical Field

TL;DR

This paper demonstrates that in a distorted optical field, atoms can experience a recoil greater than the standard limit, revealing local violations of the conventional photon momentum bound.

Contribution

The authors derive a general formula for recoil in vacuum and experimentally verify that distorted optical fields can produce extra photon recoil beyond the usual limit.

Findings

Atoms in distorted fields exhibit higher recoil than the standard limit.

A new formula for recoil calculation in vacuum is established.

Experimental measurements confirm the existence of extra recoil regions.

Abstract

Light carries momentum which induces on atoms a recoil for each photon absorbed. In vacuum, for a monochromatic beam of frequency $\nu$, the global momentum per photon is bounded by general principles and is smaller than $h \nu/c$ leading to a limit on the recoil. However, locally this limit can be broken. In this paper, we give a general formula to calculate the recoil in vacuum. We show that in a laser beam with a distorted optical field, there are regions where the recoil can be higher than this limit. Using atoms placed in those regions we are able to measure directly the extra recoil.