In a society based on the continuous exchange of sensitive data and information, the importance of secure and trustful communications is essential. Quantum key distribution (QKD) makes it possible to share data in an unconditionally secure way exploiting the basic principles of Quantum Mechanics [1]. During the last 30 years, many QKD protocols have been developed and tested, achieving long distance transmission [2] and secret key rates up to hundreds of Mbits per second [3]. However, this technology is still far from a large-scale deployment in existing fiber networks and telecom infrastructures, due to multiple factors: low secret-key rate, limited distance between users, lack of applications, high costs and high requirements in terms of low noise fiber links. In order to reveal practical issues in real-world deployments, quantum field trials have been implemented by exploiting installed fiber links on a metropolitan scale. While many of these experiments were performed on a dark fiber (thus requiring a dedicated link for quantum key transmission only), other field trials explored the coexistence between weak coherent pulses and classical signals propagating through the same fiber [4-7], see Figure 1 a). In this work we report a low-cost field trial demonstration of a complete QKD system working in the C-band telecom wavelength, performed over an installed fiber situated in Florence. A time-bin three-state protocol with one-decoy state method is implemented in the experiment [2]. As illustrated in Figure 1 b), the experimental setup consists of a transmitter (Alice), working at ch 21 of 100GHz DWDM grid, and a receiver (Bob) connected by a metropolitan dark-fiber link in a loop-back configuration. The total distance covered in the fiber link is about 40 km, with an overall transmission loss of 21 dB. Secure key generation of 3.4 kbps (in the finite key scenario) is achieved, with simultaneous transmission of a classical synchronization signal, at a different wavelength (ch 51 of 100GHz DWDM grid with -29 dBm input power), through the same fiber. In Figure 1 c) we report the secret key rate and the bit error rate, measured for several hours to prove the stability of the apparatus.
Field trial of a finite-key quantum key distribution system in the metropolitan Florence area / Bacco D.; Vagniluca I.; da Lio B.; Biagi N.; della Frera A.; Calonico D.; Toninelli C.; Cataliotti F.S.; Bellini M.; Oxenlowe L.K.; Zavatta A.. - ELETTRONICO. - 2019:(2019), pp. 0-0. ( European Quantum Electronics Conference, EQEC_2019 gbr 2019).
Field trial of a finite-key quantum key distribution system in the metropolitan Florence area
Bacco D.;Cataliotti F. S.;
2019
Abstract
In a society based on the continuous exchange of sensitive data and information, the importance of secure and trustful communications is essential. Quantum key distribution (QKD) makes it possible to share data in an unconditionally secure way exploiting the basic principles of Quantum Mechanics [1]. During the last 30 years, many QKD protocols have been developed and tested, achieving long distance transmission [2] and secret key rates up to hundreds of Mbits per second [3]. However, this technology is still far from a large-scale deployment in existing fiber networks and telecom infrastructures, due to multiple factors: low secret-key rate, limited distance between users, lack of applications, high costs and high requirements in terms of low noise fiber links. In order to reveal practical issues in real-world deployments, quantum field trials have been implemented by exploiting installed fiber links on a metropolitan scale. While many of these experiments were performed on a dark fiber (thus requiring a dedicated link for quantum key transmission only), other field trials explored the coexistence between weak coherent pulses and classical signals propagating through the same fiber [4-7], see Figure 1 a). In this work we report a low-cost field trial demonstration of a complete QKD system working in the C-band telecom wavelength, performed over an installed fiber situated in Florence. A time-bin three-state protocol with one-decoy state method is implemented in the experiment [2]. As illustrated in Figure 1 b), the experimental setup consists of a transmitter (Alice), working at ch 21 of 100GHz DWDM grid, and a receiver (Bob) connected by a metropolitan dark-fiber link in a loop-back configuration. The total distance covered in the fiber link is about 40 km, with an overall transmission loss of 21 dB. Secure key generation of 3.4 kbps (in the finite key scenario) is achieved, with simultaneous transmission of a classical synchronization signal, at a different wavelength (ch 51 of 100GHz DWDM grid with -29 dBm input power), through the same fiber. In Figure 1 c) we report the secret key rate and the bit error rate, measured for several hours to prove the stability of the apparatus.
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