From Event: SPIE Optical Engineering + Applications, 2016
Quantum key distribution (QKD) allows for communication with security guaranteed by quantum theory. The main theoretical problem in QKD is to calculate the secret key rate for a given protocol. Analytical formulas are known for protocols with a high degree of symmetry, since symmetry simplifies the analysis. However, experimental imperfections break symmetries, hence the effect of imperfections on key rates is difficult to estimate. Furthermore, it is an interesting question whether (intentionally) asymmetric protocols could outperform symmetric ones. In this work, we develop a robust numerical approach for calculating the key rate for arbitrary discrete-variable QKD protocols. This will allow researchers to study “unstructured” protocols, i.e., those that lack symmetry. Our approach relies on transforming the key rate calculation to the dual optimization problem, which dramatically reduces the number of parameters and hence the calculation time. We illustrate our method, first, by reproducing known literature results for some famous QKD protocols and, second, by investigating some unstructured protocols for which the key rate was previously unknown. Ultimately our vision is to develop user-friendly software that will allow researchers to assess the performance of any QKD protocol simply by running a MATLAB script on their laptop computer. We have taken a step towards that goal by making the key rate calculation more time-efficient. Further details about our work can be found in the following preprint: http://arxiv.org/abs/1510.01294.
Patrick Coles, Eric Metodiev, and Norbert Lütkenhaus, "Unstructured quantum key distribution
(Conference Presentation)," Proc. SPIE 9980, Quantum Communications and Quantum Imaging XIV, 99800P (Presented at SPIE Optical Engineering + Applications: August 29, 2016; Published: 7 December 2016); https://doi.org/10.1117/12.2238028.5178981872001.
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