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Maintenance-free wavelength-division-multiplexing quantum key distribution for 30 days was achieved through a 22-km field fiber. Using polarization-independent interferometers and stabilization techniques, we attained a quantum bit error rate as low as 1.70% and a key rate as high as 229.8 kbps, making the record of total secure key of 595.6 Gbits accumulated over an uninterrupted operation period. References and links1. ID Quantique, http://www.idquantique.com. 2. MagiQ Technologies, Inc., http:-speed wavelength-division multiplexing quantum key distribution system," Opt. Lett. 37(2), 223-225 (2012). "High-speed quantum key distribution system for 1-Mbps real-time key generation," IEEE J.

The theoretically proven security of quantum key distribution (QKD) could revolutionise how information exchange is protected in the future [1,2]. Several field tests of QKD have proven it to be a reliable technology for cryptographic key exchange and have demonstrated nodal networks of point-to-point links [3][4][5]. However, so far no convincing answer has been given to the question of how to extend the scope of QKD beyond niche applications in dedicated high security networks. Here we show that adopting simple and cost-effective telecommunication technologies to form a quantum access network can greatly expand the number of users in quantum networks and therefore vastly broaden their appeal. We are able to demonstrate that a high-speed single-photon detector positioned at a network node can be shared between up to 64 users for exchanging secret keys with the node, thereby significantly reducing the hardware requirements for each user added to the network. This point-to-multipoint architecture removes one of the main obstacles restricting the widespread application of QKD. It presents a viable method for realising multi-user QKD networks with resource efficiency and brings QKD closer to becoming the first widespread technology based on quantum physics.In a nodal QKD network multiple trusted repeaters are connected via point-to-point links between a quantum transmitter (Alice) and a quantum receiver (Bob). These point-to-point links can be realised with long-distance optical fibres, and in the future might even utilize ground to satellite communication [6][7][8]. While point-to-point connections are suitable to form a backbone quantum core network to bridge long distances, they are less suitable to provide the last-mile service needed to give a multitude of users access to this QKD infrastructure. Reconfigurable optical networks based on optical switches or wavelength-division multiplexing have been suggested to achieve more flexible network structures[3, 9-12], however, they also require the installation of a full QKD system per user, which is prohibitively expensive for many applications.Giving a multitude of users access to the nodal QKD network requires point-to-multipoint connections. In modern fibre-optic networks point-to-multipoint connections are often realized passively using components such as optical power splitters [13]. Single photon QKD with the sender positioned at the network node and the receiver at the user premises[14] lends itself naturally to a passive multi-user network (see Fig. 1a). However, this downstream implementation has two major shortcomings. Firstly, every user in the network requires a single photon detector, which are often expensive and difficult to operate. And secondly, it is not possible to deterministically address a user. All detectors therefore have to operate at the same speed as the transmitter in order not to miss photons, which means most of the detector bandwidth is unused.Here, we show that both problems associated with a downstream implementation can be overcome ...

We analyse the finite-size security of the efficient Bennett-Brassard 1984 protocol implemented with decoy states and apply the results to a gigahertz-clocked quantum key distribution system. Despite the enhanced security level, the obtained secure key rates are the highest reported so far at all fibre distances.

Quantum key distribution (QKD) uniquely allows distribution of cryptographic keys with security verified by quantum mechanical limits. Both protocol execution and subsequent applications require the assistance of classical data communication channels. While using separate fibers is one option, it is economically more viable if data and quantum signals are simultaneously transmitted through a single fiber. However, noise-photon contamination arising from the intense data signal has severely restricted both the QKD distances and secure key rates. Here, we exploit a novel temporal-filtering effect for noise-photon rejection. This allows high-bit-rate QKD over fibers up to 90 km in length and populated with error-free bidirectional Gb/s data communications. With high-bit rate and range sufficient for important information infrastructures, such as smart cities and 10 Gbit Ethernet, QKD is a significant step closer towards wide-scale deployment in fiber networks.