Asymmetric Cloning to Eavesdrop on BB84 Protocol

The BB84 Protocol is a method of Quantum Key Distribution (QKD) introduced by Bennett and Brassard in 1984, which—theoretically—has perfect security. However, actualization of quantum computers with current technology does not guarantee the conditions necessary for such a level of security. The fidelity of the QPU (noise inherent in the system) reduces the accuracy of transmissions. By leveraging the inherent loss expected in the system, an eavesdropper may obtain actionable information [on the raw key] with sufficiently low disturbance to the signal to remain nearly undetectable. In this talk we will demonstrate how this is possible and the tradeoff between information gain and detectability. Our work is based on theoretical evaluation of the method of asymmetric phase-covariant cloning and experimentation on a trapped ion quantum computer.