Theorem: Model 3 record

At the selected finite $\Lambda ,M$, the generator

has a positive vacuum–coherent Ramsey contrast for every $\lambda \ne 0$, at a sufficiently small fixed $\tau >0$ and $\theta =\pi /2$. At $\lambda =0$, the record laws agree exactly. If the declared source response is multiplied by an additional classical strength $\zeta$, the source-off control $\zeta =0$ also gives exact agreement.

Proof. The mean separation is at least $|\lambda |d_3/2$, and both second moments are finite by boundedness. Apply Lemma lem:contrast. At either off-control, $U=I$, so $p_s=(1+s\cos \theta )/2$, independently of the preparation.