  Quantum cryptography is set to become a key technology for future secure
communications. However, to get maximum benefit in communication networks,
transmission links will need to be shared among several quantum keys for
several independent users. Such links will enable switching in quantum network
nodes of the quantum keys to their respective destinations. In this paper we
present an experimental demonstration of a photonic integrated silicon chip
quantum key distribution protocols based on space division multiplexing (SDM),
through multicore fiber technology. Parallel and independent quantum keys are
obtained, which are useful in crypto-systems and future quantum network.
