Diffusion induced decoherence of stored optical vortices

Abstract

We study the coherence properties of optical vortices stored in atomic ensembles. In the presence of thermal diffusion, the topological nature of stored optical vortices is found not to guarantee slow decoherence. Instead the stored vortex state has decoherence surprisingly larger than the stored Gaussian mode. Generally, the less phase gradient, the more robust for stored coherence against diffusion. Furthermore, calculation of coherence factor shows that the center of stored vortex becomes completely incoherent once diffusion begins and, when reading laser is applied, the optical intensity at the center of the vortex becomes nonzero. Its implication for quantum information is discussed. Comparison of classical diffusion and quantum diffusion is also presented.

5 pages, 2 figures

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• Storing images in warm atomic vapor
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• Transfer of orbital angular momentum of light using two component slow light
• Transfer of optical vortices in coherently prepared media
• Complete energy conversion between light beams carrying orbital angular momentum using coherent population trapping for a coherently driven double-Λatom-light coupling
• Spatial mode storage in a gradient echo memory
• Slow polaritons with orbital angular momentum in atomic gases
• Coherent Diffusion of Polaritons in Atomic Media
• Optical vortices of slow light using tripod scheme
• Image Storage in Hot Vapors
• Transverse azimuthal dephasing of vortex spin wave in a hot atomic gas