Maximizing Secret Key Extraction from Quantum Cryptographic Systems

Abstract

While quantum key distribution (QKD) has been established as a theoretically secure way of sharing secret keys between two remote users who have never had prior communications, it is susceptible to detector-side channel attacks due to imperfect hardware. Measurement-device-independent quantum key distribution (MDI-QKD) systems promise to eliminate all known and unknown detector side-channel attacks and is practical with current technology. This thesis serves as a brief exploration into the intricacies of MDI-QKD.

In this project, a general introduction to QKD in general and MDI-QKD in particular is given, both theoretically and experimentally. Of note is free-space QKD, particularly with satellites, which has been of keen scientific interest of late. Next, a model was progressively built that realistically simulates a general MDI-QKD setup with no assumptions on its implementation parameters. The model was then used to derive several results concerning the performance characteristics of real-world MDI‑QKD systems. Finally, an optimization problem was considered to assist in maximizing key extraction during parameter estimation, a step necessary in the MDI-QKD protocol.

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