Uncomputation

If an available unitary $U$ has transformed ${\rho }_{QC}\otimes |0⟩⟨0{|}_S$, applying $U^{†}$ to the same required registers restores that joint state, including $Q$. This is reversible uncomputation. It need not remain available after a required register has been discarded. The distinction is consistent with reversible-computation methods Bennett1973.

It is not a rule for cloning an unknown output before uncomputing, and it is not a reusable-memory thermal reset certificate.