Probing quantum cores of optical vortices with atoms

Optical vortices are points of zero intensity in a two dimensional, classical optical field. As first discussed by Berry and Dennis [Berry, M. V. and Dennis, M. R., "Quantum cores of optical phase singularities" Journal of Optics A 6, S178-S180 (2004)] these singularities are replaced by 'quantum cores' in a deeper level of description. In a fully quantized theory of optical fields an excited atom trapped at the singularity can emit light spontaneously and hence soften the perfect zero of an optical vortex. More recently Barnett [Barnett, S. M., "On the quantum cores of a optical vortex," Journal of Modern Optics 55, 2279-2292 (2008)] presented a more realistic analysis of quantum cores which accounts for the effect of the trapping potential on the transition dynamics inside a vortex core. Here, we revisit the scenario of emission near an optical vortex in the realistic setting of Barnett.