Analytical Bounds for Dynamic Multi-Channel Discrimination

The ability to precisely discriminate multiple quantum channels is fundamental to achieving quantum enhancements in data-readout, target detection, pattern recognition, and more. Optimal discrimination protocols often rely on entanglement shared between an incident probe and a protected idler-mode. While these protocols can be highly advantageous over classical ones, the storage of idler-modes is extremely challenging in practice. In this work, we explicitly define idler-free protocols based on the use of multipartite entangled probe states. We show that using non-disjoint distributions of multipartite probe states over multi-channels can be described by dynamic discrimination protocols. Analytical bounds for their error probabilities are derived for arbitrary pattern size, revealing idler-free protocols that display performance close to idler-assistance for powerful, near-term quantum sensing applications.