Abstract
The development and wide application of quantum technologies highly depend on the capacity of the communication channels distributing entanglement. Space-division multiplexing (SDM) enhanced channel capacities in classical telecommunication and bears the potential to transfer the idea to quantum communication using current infrastructure. Here, we demonstrate an SDM of polarization-entangled photons over a 411m long 19-core multicore fiber distributing polarization-entangled photon pairs through up to 12 channels simultaneously. The quality of the multiplexed transfer is evidenced by high polarization visibility and CHSH Bell inequality violation for each pair of opposite cores. Our distribution scheme shows high stability over 24 hours without any active polarization stabilization and can be effortlessly adapted to a higher number of channels. This technique increases the quantum-channel capacity and allows the reliable implementation of quantum networks of multiple users based on a single entangled-photon pair source.
Highlights
Quantum communication has been rapidly progressing in private and secure information transmission [1,2,3,4]
Space-division multiplexing (SDM) is currently being investigated in the classical communications context [12]. This multiplexing approach relies on few-mode [13,14], multimode [15], and multicore fibers [16,17,18], as well as novel mutiplexers and demultiplexers [19,20] to harness the spatial dimension of light and boost capacity compared to single-mode fiber systems
Our results show that quantum SDM can be achieved by exploring intrinsic momentum correlations in the spontaneous parametric down-conversion (SPDC) process, which is not possible via random distribution of the photons
Summary
Quantum communication has been rapidly progressing in private and secure information transmission [1,2,3,4]. Major types of channels are free-space links [5,6], satellite [7], and optical fibers [8,9,10], where fiber connections are the easiest and already deployed option for the last mile connection to the customers In this context, a vital aspect of optimizing resources is the development and implementation of high-capacity quantum channels. To the best of our knowledge, this is the first experimental realization of a polarization-entanglement distribution scheme based on momentum correlation over a MCF and the simultaneous use of quantum correlations in multiple degrees of freedom. Our results show that quantum SDM can be achieved by exploring intrinsic momentum correlations in the spontaneous parametric down-conversion (SPDC) process, which is not possible via random distribution of the photons
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