Wavelength division multiplexing of continuous variable quantum key distribution and 18.3 Tbit/s data channels

TLDR

Quantum key distribution offers unconditional security and is a promising technology for next‑generation communication systems, but its commercial success depends on integrating QKD signals into existing fiber‑optic networks. This study experimentally verifies that a continuous‑variable QKD channel can co‑propagate with a large number of wavelength‑division‑multiplexed coherent data channels. The experiment used 100 erbium‑doped‑fiber‑amplified, polarization‑multiplexed 16‑ary QAM data channels, achieving a total classical bitrate of 18.3 Tbit/s alongside the QKD signal. Over a 24‑hour run, the system produced a secret key, demonstrating more than a tenfold increase in the number of co‑propagated channels and a 90‑fold increase in classical bitrate compared to previous C‑band co‑propagation results.

Abstract

Abstract Quantum key distribution (QKD) can offer communication with unconditional security and is a promising technology to protect next generation communication systems. For QKD to see commercial success, several key challenges have to be solved, such as integrating QKD signals into existing fiber optical networks. In this paper, we present experimental verification of QKD co-propagating with a large number of wavelength division multiplexing (WDM) coherent data channels. We show successful secret key generation over 24 h for a continuous-variable QKD channel jointly transmitted with 100 WDM channels of erbium doped fiber amplified polarization multiplexed 16-ary quadrature amplitude modulation signals amounting to a datarate of 18.3 Tbit/s. Compared to previous co-propagation results in the C-band, we demonstrate more than a factor of 10 increase in the number of WDM channels and more than 90 times higher classical bitrate, showing the co-propagation with Tbit/s data-carrying channels.