(OSA) Researchers release new study:  “Plug and play continuous variable quantum key distribution for metropolitan networks”, published by partners of the CiViQ project. The plug-and-play CV-QKD system demonstrated in this paper has the potential to become an effective low-cost solution for securing short-reach metropolitan networks.
The plug-and-play continuous variable quantum key distribution system (CV-QKD) is Gaussian modulated quadratures and a true local oscillator.
Quantum key distribution (QKD) is the most prominent quantum cryptographic protocol as it allows two remote network nodes to generate an ultra-secure encryption key. At the moment, there are two main QKD protocols: discrete variable (DV) and continuous variable (CV). While DV-QKD heavily relies on single photon detector technology, CV-QKD provides security through shot-noise limited coherent detection. The CiViQ project uses Continuous-Variable (CV) QKD technology as it offers the potential for flexible, software defined systems that can be readily integrated in innovative and upgradable dynamic network architectures.
Typically, plug-and-play QKD systems suffer from Rayleigh back-scattering noise generated by the high power laser signal simultaneously transmitted with the quantum signal at the same wavelength and fiber channel. The Rayleigh back-scattering noise limits the performance and the maximum secure communication distance of the system compared to one-way CV-QKD protocols. In this paper, researchers propose a plug-and-play CV-QKD system that minimizes the noise from Rayleigh back-scattering by using two independent fiber strands for the distribution of the laser and the transmission of the quantum signals.

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