Implementation of space-division multiplexed entanglement-based quantum cryptography over multicore fiber

Abstract

Quantum key distribution has shown promising advances in information transmission security. In particular, quantum communication schemes based on entanglement have enormous potential to enhance the security and efficiency of information transmission. Therefore, today’s efforts address overcoming issues related to high data transmission and long-distance implementations to enable real-world quantum communication applications. Here, we experimentally demonstrate a multiplexing technique to enhance the secret key rate by exploiting the momentum correlation of photon pairs generated by spontaneous parametric downconversion. We distributed polarization-entangled photon pairs into opposite cores within a 19-core multicore fiber. We estimated the secret key rates in a configuration with 6 and 12 cores from the entanglement visibility after transmission through a 411-m-long multicore fiber. Our results can lead to the transmission of more information per photon and the establishment of novel quantum networks with one common communication channel, which opens the possibility of deploying new quantum channels over longer distances.