Question, contribution, and corrections

Oai265-A separated selected output entropy from reference-preserving recovery Oai265A. The present question is operational:

Given a specified memory, a fixed implemented decoder, complete attempted-run records, and calibrated preparation and measurement, what finite-confidence statement can be made about arbitrary-input quantum recovery?

Direct fidelity estimation, quantum process certification, channel distances, and their statistical foundations are established subjects KlieschRoth,FlammiaLiu,DaSilvaEtAl,Watrous. Our contribution is a self-contained protocol and error budget assembled for this particular qubit-memory task. The Choi conversion and diamond-norm interpretation are not claimed as new.

The supplied Cheung manuscripts provide documentary interfaces: En07-C distinguishes selected diagnostics from complete channels; Hawk04-B gives dimension-explicit decoder certificates; En02-B/C retain all decoder branches; and En01-C separates complete-record statistics from calibration coverage CheungEn07C,CheungHawk04B,CheungEn02B,CheungEn02C,CheungEn01C. Their model-specific results are comparisons, not unprovided premises of the proofs below.