We demonstrate a simple projective measurement based on the quantum eraserconcept that can be used to characterize the disturbances of any communicationchannel. Quantum erasers are commonly implemented as spatially separated pathinterferometric schemes. Here we exploit the advantages of redefining thewhich-path information in terms of spatial modes, replacing physical paths withabstract paths of orbital angular momentum (OAM). Remarkably, vector modes(natural modes of free-space and fiber) have a non-separable feature ofspin-orbit coupled states, equivalent to the description of two independentlymarked paths. We explore the effects of fiber perturbations by probing astep-index optical fiber channel with a vector mode, relevant to high-orderspatial mode encoding of information for ultra-fast fiber communications.
展开▼
