Abstract

Light beams carrying orbital angular momentum (OAM) have attracted a great interest owing to their several applications ranging from the mechanical manipulation of macroscopic particles to the encoding of quantum information [1]. A well-known family of these beams is constituted by Laguerre-Gaussian modes specified by a topological charge ℓ, which gives to the mode a helicoidal phase structure and a corresponding OAM per photon equal to ℓħ. The nonlinear interaction of these beams with atomic systems has been investigated via four-wave mixing processes and the corresponding conservation of OAM demonstrated both in cold and thermal atoms [2]. The storage of OAM in cold and thermal atomic ensembles was also previously demonstrated [3].

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