Picture of virus under microscope

Research under the microscope...

The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs.

Strathprints serves world leading Open Access research by the University of Strathclyde, including research by the Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), where research centres such as the Industrial Biotechnology Innovation Centre (IBioIC), the Cancer Research UK Formulation Unit, SeaBioTech and the Centre for Biophotonics are based.

Explore SIPBS research

On the quantum core of an optical vortex

Barnett, S.M. (2008) On the quantum core of an optical vortex. Journal of Modern Optics, 55 (14). pp. 2279-2292.

Full text not available in this repository. (Request a copy from the Strathclyde author)

Abstract

An optical vortex is a line around which the phase increases by an integer multiple of 2π. It follows that the phase on the line itself is undefined and hence the field must have zero amplitude there. Berry and Dennis have suggested that this line of darkness is smoothed by a 'quantum core' with a radius proportional to 1/2 and have illustrated this idea by considering the competition between stimulated and spontaneous emission by an excited atom placed in the vicinity of the vortex. We show here that a similar phenomenon may be seen in absorption when the quantum state of motion of the absorbing atom is taken into consideration. There is, however, an underlying quantum singularity in which the absorption events for an atom centred on the vortex core can take place only if accompanied by a transfer of angular momentum to the atomic motion. The nature of this singularity relies on the evolution of an entangled state between the electronic and motional degrees of freedom of the trapped atom. We comment briefly on the effects of field quantisation on this quantum core of the optical vortex.