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QI: Fachverband Quanteninformation
QI 36: Poster – Quantum Information (joint session QI/Q)
QI 36.53: Poster
Donnerstag, 13. März 2025, 17:00–19:00, Tent
Employing Two-Photon Interference to Secure QKD Against Optical Side Channels — •Franziska Divkovic1, Moritz Birkhold1,2, Harald Weinfurter1,2,3, and Lukas Knips1,2,3 — 1Ludwig Maximilian University, Munich, Germany — 2Munich Center for Quantum Science and Technology, Munich, Germany — 3Max Planck Institute of Quantum Optics, Garching, Germany
Quantum Key Distribution (QKD) provides a key advantage over classical cryptography by enabling secure communication without the risk of unnoticed eavesdropping on the quantum channel. However, in real devices, side channels - additional degrees of freedom (DOFs) correlated with the one used to encode the key - can allow eavesdroppers to extract information. If not quantified, these side channels can compromise the security of the QKD scheme.
A key assumption in the security proof is the phase randomization of consecutive pulses representing the same symbol. Indistinguishable pulses, which are phase-randomized, prevent attacks by ensuring no information can be extracted from alternate DOFs. To verify whether this criterion is met, the interference of these pulses is investigated. Additionally, the interference of pulses representing different symbols is analyzed to assess their indistinguishability across all except polarization. The visibility of the interference pattern serves as a key metric for quantifying pulse indistinguishability and security. This is achieved using a fiber-based interferometer with a delay line in one arm and a polarization-cleaning mechanism. This research provides insights for defining specifications and developing tests to secure against attacks.
Keywords: QKD; Quantum Key Distribution; Two-Photon Interference; Quantum Communication