Abstract
We demonstrate quantum key distribution (QKD) with classical signals in a seven-core fiber using dense wavelength division multiplexing. Quantum signals are transmitted in an outer core separately and intercore crosstalk (IC-XT) is the main impairment of them. In order to alleviate IC-XT, we propose a quantum-classical interleave scheme. Then the properties of IC-XT are analyzed based on the measurement results, which indicate counter-propagation is a better co-existence method than co-propagation. Finally, we perform QKD experiments in the presence of two classical channels with a channel spacing of 100 GHz between quantum channel and the nearest classical channels. The experiment results prove counter-propagation almost immune to IC-XT, which is consistent with our analysis. Also, the feasibility of the transmission over the range of metropolitan area networks is validated with our scheme.
Highlights
Q UANTUM key distribution (QKD) is the most successful application in quantum information science at present
We propose a wavelength-space division multiplexing (WSDM) scheme of QKD and classical signals
The results show that the total power of classical signals in the nearest cores mainly determines the power of IC-XT in quantum core
Summary
Q UANTUM key distribution (QKD) is the most successful application in quantum information science at present. [23] presented the first QKD experiment in multicore fiber (MCF) They proposed an experiment in which a quantum signal and classical signal were transmitted together in a MCF. In a large capacity transmission system, this transmission scheme is obviously a waste of wavelength resources To this end, we propose a wavelength-space division multiplexing (WSDM) scheme of QKD and classical signals. Dense wavelength division multiplexing (DWDM) is used in each core and separation between quantum channels and the nearest classical channels can reach 50 GHz. The main impairment of QKD in our scheme is the intercore crosstalk (IC-XT) from the classical signals. The experiment results validate the feasibility for the transmission over the range of metropolitan area networks (typically 30 km) with our scheme
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