In order to assess the susceptibility of the quantum key distribution (QKD) systems to the hacking attack including simultaneous and frequent system self-decalibrations, we analyze the stability of the QKD transmission organized in two commercially available systems. The first one employs non-entangled photons as flying qubits in the dark quantum channel for communication whereas the second one utilizes the entangled photon pairs to secretly share the cryptographic key. Applying standard methods of the statistical data analysis to the characteristic indicators of the quality of the QKD communication (the raw key exchange rate [RKER] and the quantum bit error rate [QBER]), we have estimated the pace of the self-decalibration of both systems and the repeatability rate in the case of controlled worsening of the dark channel quality.
We have performed a series of feasibility tests toward deployment of quantum key distribution (QKD) systems in commercial optical fiber TELECOM network. By monitoring of the operation of selected state-of-the-art QKD systems with a typical commercial imperfect communication line in the role of quantum dark channel we have assessed stability and reliability of two quantum cryptography systems, on nonentangled and on entangled photons. The quantum bit error was the main observed parameter which allowed for quantitative assessment of both systems operation efficiency and their resistivity to random perturbations including hacker attacks in noisy environment. The comparison of both systems with respect to their tolerance against noise and technical imperfections of a dark quantum channel has been presented.
In this communication, we report results of running tests on standard telecommunication metropolitan network 1550 nm fiber applied to a quantum channel to EPR S405 Quelle prototype systems installed in National Laboratory for Quantum Technologies WUT and in CompSecur Wroclaw. Testing was carried out by means of the original design by us and applied special data card collecting parameters of functioning system allowing for assessment of quality of quantum channel. We have performed several trials using various configurations of standard 1550 nm fiber patch-cord up to length of 6.5 km with additional usage of various patch-cords with weldings and connectors which typically present in already installed commercial metropolitan communication networks. The implementation of this testing indicated that the rigorous maintenance of photon polarization is required for quantum information exchange upon EPR S405 Quelle functioning. The polarization of optical signal turned out to be, however, very unstable for the tested connection which resulted in very rapid QBER rise precluding practical usefulness of this connection for secure quantum exchange of cryptographic key over practically significant distances. We have identified that the main obstacle was the polarization decoherence caused by weldings and connectors in standard patch-cords and accidental strains in fibers as well as generally poor transmitting properties of 1550 nm fiber for much shorter wavelength photons used by the Quelle system. To maintain the quantum channel active, very frequent manual corrections of polarization control were required. So we expect that by design and application of an automatic polarization control module, one would stabilize visibility ratio and lower QBER to an acceptable level conditioning possible future implementation of entangled QKD system in commercial networks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.