Sudakov

Gaussian mean width strong converse bound on the classical identification capacity of quantum channels

arXiv:2606.05032v1 Announce Type: cross Abstract: We establish a single-letter and efficiently computable strong converse bound on the classical identification capacity of quantum channels. By equipping the $n$-fold channel output space with a product state-weighted $\sigma$-Euclidean geometry, we allow trace-distance separation constraints for identification codes to be controlled by Euclidean covering estimates. Using Sudakov's inequality, we bound the covering numbers of the $n$-fold...