A secondary index for non-Fredholm operators associated with quantum walks
Toshikazu Natsume, Ryszard Nest · arXiv (Cornell University) · 2023
We study an analogue of chirality operators associated with quantum walks on the binary tree. For those operators we introduce a K-theoretic invariant, an analogue of the index of Fredholm operators, and compute its values in the ring of di-adic integers