TU Graz finds zero-retention in bottleneck quantum repeater families

Simulations of entanglement-based quantum networks reveal a vulnerability: certain repeater configurations exhibit zero retention of usable entangled states when subjected to realistic attacks. Researchers Brennan Bell (RFI-IRFOS and TU Graz), Inti Gabriel Mendoza Estrada (openmaind FlexCo and TU Graz), Andreas Trügler (Know Center Research GmbH and University of Graz), and Paul Erker (Atominstitut, TU Wien and IQOQI, ÖAW) analyzed 50 structured network topologies using a simulated Ekert-91 protocol, discovering that bottleneck families had zero retention, while non-bottleneck families followed a predictable 1 – 1/N coverage principle. The team validated their adversarial co-learning model with a Pearson correlation coefficient of 0.99 against a full-matrix minimax reference. This finding highlights the critical importance of topology in quantum communication and underscores the need for explainable security assessments, as simulator diagnostics can be easily misconstrued as definitive security claims. A complete failure of quantum repeaters…