Continuous-variable quantum key distribution over a 15 km multi-core fiber

The secure transfer of information is critical to the ever-increasing demands of the digital world. Continuous-variable quantum key distribution (CV-QKD) is a promising technology that can provide high secret key rates over metropolitan areas, using conventional telecom components. In this study, we demonstrate the utilization of CV-QKD over a 15 km multi-core fiber (MCF), in which we take advantage of one core to remotely frequency lock Bob's local oscillator with Alice's transmitter. We also demonstrate the capacity of the MCF to boost the secret key rate by parallelizing CV-QKD across multiple cores. Our results indicate that MCFs are promising for the metropolitan deployment of QKD systems.