Entanglement manipulation through multicore fibres

Multicore fibres are recently gaining considerable attention in the context of quantum communication, where their capability to transmit multiple quantum states along different cores of the same channel makes them a promising candidate for the implementation of scalable quantum networks. Here, we show that multicore fibres can be effectively used not only for the scope of communication but also for the manipulation of entangled states. Exploiting the formalism of completely positive trace-preserving maps, we describe the action of a multicore fibre as a quantum channel and investigate the propagation of a transmitted state under the effect of decoherence and inter-core crosstalk. Then, we propose a novel protocol for the manipulation of the entanglement where, starting from a maximally entangled state of two qudits, we use a multicore fibre to create new families of mixed entangled states. Notably, the presence of crosstalk is fundamental for the generation of such states.