Derivation and structural analysis of the ratio map R (α) =21+2−αR () =21+2^{-}R (α) =1+2−α2 arising in dynamical-decoupling noise spectroscopy. The work develops its combinatorial origin, Parseval weight structure, logistic and operator-mean representations, Fisher/fragility geometry, and multi-ratio protocol design framework.
Hiroyuki Shioiri (Mon,) studied this question.