Topological Charge Detection of Magnetic Monopoles: A Conceptual Proposal Exploiting the Witten Effect

We propose a novel detection concept for cosmic magnetic monopoles based on the Witten effect in topological insulators. A magnetic monopole traversing a topological insulator with topological angle θ = π acquires fractional electric charge q = e/2, enabling detection via direct charge measurement. Unlike velocity-dependent ionization or Cherenkov mechanisms, this topological response remains effective for slow galactic monopoles (β ∼ 10−4 to 10−3), addressing a critical gap in current experimental coverage. We present the theoretical foundation, outline a layered detector geometry, and propose a validation pathway beginning with material characterization and small-scale proof-of principle experiments. While significant technical challenges remain, particularly in charge collection efficiency and background discrimination, this approach offers a fundamentally new detection channel. This work serves as an invitation for experimental collaboration to realize these concepts.