S. Wengerowsky

Sören Wengerowsky, Siddarth Koduru Joshi, Fabian Steinlechner, Julien R. Zichi, Sergiy M. Dobrovolsky, Rene van der Molen, Johannes W. N. Los, Val Zwiller, Marijn A. M. Versteegh, Alberto Mura, Davide Calonico, Massimo Inguscio, Bo Liu, Thomas Scheidl, Hannes Hübel, Anton Zeilinger, André Xuereb and Rupert Ursin
We present the distribution of polarisation-entangled photons between Malta and Sicily using a 96 km-long submarine telecommunications as a quantum channel. We were able to observe around 260 photon pairs per second, with a polarisation visibility above 86%. In a second experiment we send one of the entangled photons through this cable back and forth such that two of the deployed fibres were used consecutively as a loop. Our experiment demonstrates the feasibility of using deployed submarine telecommunications optical fibres as long-distance quantum channels for polarisation-entangled photons. This opens up possibilities for future experiments and technological applications using existing infrastructure.

Soeren Wengerowsky, Siddarth Koduru Joshi, Fabian Steinlechner, Hannes Hübel and Rupert Ursin
We present a proof-of-principle experiment consisting of four users in a novel network architecture which enables scalable quantum communication based on polarization-entangled photon pairs at telecommunications wavelength. Our scheme uses frequency multiplexing to share 6 two-photon entangled states between each pair of clients in a mesh-like network topology using only one fiber per client. As clients need minimal resources - one polarization detection module and single-mode fiber each, the physical topology of the network outside the source scales linearly if a user is added, while the logical topology scales quadratically with N(N-1) network connections between N users."