Experimental Space-Division Multiplexed Polarization-Entanglement Distribution through 12 Paths of a Multicore Fiber

To enable the quantum communication revolution, it is necessary to develop strategies that allow the distribution of quantum correlations reliably and, in particular, with high throughput. In classical telecommunication, high data throughput is achieved by multiplexing, e.g., through multicore fibers, a technique indispensable in modern communication networks. In their recent work published in PRX Quantum, Evelyn A. Ortega and coworkers from IQOQI Vienna, The University of Central Florida, and Universidade Federal de São Carlos demonstrated the multiplexed distribution of quantum entanglement through up to 12 cores of a multicore simultaneously. These results allow for resource-efficient high-rate quantum communication and enable entanglement distribution in multi-user networks.

Ortega et al. experimentally demonstrated the multiplexing of quantum signals by space-division multiplexing over a multicore fiber. To this end, they generated polarization-entanglement photon pairs at telecommunication wavelengths and distributed several pairs simultaneously and independently through 6 and 12 cores of the multicore fiber. Exploiting quantum correlations in different degrees of freedom of the generated photon pairs, the researchers deterministically coupled and transmitted entangled photons pairs through dedicated cores of the multicore fiber. In this way, the polarization-entangled photon pairs were efficiently coupled into opposite cores of the centrally-symmetric multicore fiber. Ortega and collaborators certified the high quality of this separation through intensity-correlations measurements between the different cores and high fidelity in the polarization measurements for the spatially correlated cores, implementing deterministic multiplexing up to twelve cores simultaneously.


The presented method allows to increases the data transmission in quantum communication protocols drastically by exploiting otherwise unused quantum correlations. In combination with other quantum multiplexing and encoding techniques, this approach provides a pathway towards high-rate quantum communication for the future quantum internet.