Manuscript VII-E@1 · VII-E.tex · definition · b713cf3c

Definition: Coherent recording

Types, states, and external geometry › Three measurement interfaces · lines 445–456

VII-E@1#def:coherent, VII-E@1#eq:record-isometry

A fresh quantum carrier $A$ , with basis indexed by $Z$ , is introduced by the isometry

V (∣ z ⟩_{S} \otimes ∣ b ⟩_{B}) = ∣ z ⟩_{S} \otimes ∣ z ⟩_{A} \otimes ∣ b ⟩_{B} .

The corresponding channel is $Copy_{S} (ρ) = V ρ V^{†}$ . It returns both $S$ and $A$ .

Displayed formulas in this passage

VII-E@1#eq:record-isometry · line 449
$V (∣ z ⟩_{S} \otimes ∣ b ⟩_{B}) = ∣ z ⟩_{S} \otimes ∣ z ⟩_{A} \otimes ∣ b ⟩_{B} .$