High-dimensional decoy-state quantum key distribution over 0.3 km of multicore telecommunication optical fibers

TL;DR

This paper demonstrates a stable, secure high-dimensional quantum key distribution over 0.3 km of multicore fiber, achieving positive secret key rates up to 25 km, advancing quantum communication infrastructure.

Contribution

It introduces a practical method for high-dimensional quantum key distribution using multicore fibers compatible with existing telecom infrastructure.

Findings

Secure key distribution over 0.3 km multicore fiber

Positive secret key rate up to 25 km

Compatibility with current telecommunication systems

Abstract

Multiplexing is a strategy to augment the transmission capacity of a communication system. It consists of combining multiple signals over the same data channel and it has been very successful in classical communications. However, the use of enhanced channels has only reached limited practicality in quantum communications (QC) as it requires the complex manipulation of quantum systems of higher dimensions. Considerable effort is being made towards QC using high-dimensional quantum systems encoded into the transverse momentum of single photons but, so far, no approach has been proven to be fully compatible with the existing telecommunication infrastructure. Here, we overcome such a technological challenge and demonstrate a stable and secure high-dimensional decoy-state quantum key distribution session over a 0.3 km long multicore optical fiber. The high-dimensional quantum states are defined in terms of the multiple core modes available for the photon transmission over the fiber, and the decoy-state analysis demonstrates that our technique enables a positive secret key generation rate up to 25 km of fiber propagation. Finally, we show how our results build up towards a high-dimensional quantum network composed of free-space and fiber based links