A Catalytic Algorithm for Transposing Unknown Qutrit Unitaries with Tight Query Bounds

We construct exact deterministic circuits for transposing and inverting an unknown qutrit unitary U in SU(3) using only forward queries. Three queries prepare a catalyst independently of the input state. Four further queries implement transposition while returning the catalyst unchanged and uncorrelated with the output. Two uses within an antisymmetric encoding implement inversion with eight processing queries and return the same catalyst. Reusing the catalyst implements m transpositions or inversions with 3+4m or 3+8m total queries, respectively. More generally, we prove that exact transposition and inversion of an unknown U in SU(d), d 2, require at least d+1 and d 2-1 processing queries, respectively, in fixed causal order. These processing bounds hold for any program state prepared independently of the input state using finitely many forward queries, even if that state is consumed during processing. Both our catalytic qutrit algorithms attain their respective bounds. Moreover, exact qutrit transposition with four processing queries requires at least three preparation queries, and our construction attains this bound.