Manuscript Oai279-A@1 · Oai279-A.tex · proposition · a1abc73f

Proposition: Arbitrarily small noise can destroy the certificate

Stage 2: price the comparisons, not a missing algorithm › A small implementation budget is not exactness · lines 1217–1243 · proof included or linked

Oai279-A@1#prop:noise

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For every , there is a CPTP implementation perturbation of the finite circuit at half-diamond distance at most whose output on is incorrect with probability exactly .

Proof. After the ideal circuit, apply

where flips output wire . The two branches are CPTP. The half-diamond distance from the identity is at most , by convexity and the maximum channel distance one Watrous.

In the ideal output, wire is the only one bit of the first prime entry . Flipping it changes that entry to zero while leaving the later entries positive. The resulting word is not a valid zero-padded prime list for . Thus exactly the perturbed branch is wrong, with probability .

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