Readout does not reconstruct an arbitrary quantum input

Equation (eq:readout-drop) is destructive readout with a retained classical record. It is compatible with exact evaluation of a classical function. It is not a reference-preserving quantum recovery channel.

This is the appropriate scope of the readout and recovery comparisons in Cheung's I, VIII-B, En07-A, and Hawk04-B CheungI,CheungVIIIB,CheungEn07A,CheungHawk04B. A typed output interface cannot supply an unconstructed arithmetic algorithm, and an arithmetic output cannot supply a gravitational dictionary.