Entanglement of the Hermite-Gaussian modes states of photons

We found that the Hermite-Gaussian (HG) modes of the down converted beams from the spontaneous parametric down conversion are quasi-conserved and the generated photon pairs are HG modes entangled for some special cases. This is valuable for either the investigation of fundament properties of multi-dimensional entanglement or quantum information applications. (c) 2005 Elsevier B.V. All rights reserved.