Optomechanics and orbital angular momentum
The interplay between optical modes and mechanical modes gives rise to a rich variety of effects that have been theoretical and experimental explored in optomechanics research area. In the quantum regime the optomechanical systems can access at quantum behaviour of objects on the unprecedented scales, open the way to manipulate the quantum state of macroscopic objects . In the most of the configurations the optical and mechanical modes exchange linear momentum. However the light can also transfer angular momentum to matter. In pioneering Beth’s experiment only the spin part of the photon angular momentum was involved in the angular manipulation of macroscopic objects, afterwards Allen et al. in 1992 pointed out the possibility to observe the torque produced also by the photon orbital angular momentum (OAM) part. The OAM is encoded in the spatial transverse profile of the optical beam, unlike spin, the OAM can in principle take unlimited value, lћ. This unique peculiarity has attracted much interests in the quantum information and communication fields. It is possible to transfer a wealth of information between different nodes of a quantum network exploiting flying qudits carrying OAM in a multi-dimensional Hilbert space. H. Shi and M. Bhattacharya proposed a quantum optomechanical memory for photons with OAM. We propose to exploit the optomechanical coupling between ultra-low dissipation mechanical microresonator and OAM beam. The torsional mechanical modes will couples with optical OAM modes storing and transferring with high fidelity the information codified in OAM .
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