= Two-component Bell resource in dense coding
{title2=$|\chi\rangle=a|\Phi^+\rangle+b|\Phi^-\rangle,\quad|a|^2+|b|^2=1$}
With phase/parity labels $(u,v)$ encoded by $X^vZ^u$, a resource $a|\Phi^+\rangle+b|\Phi^-\rangle$ gives intended-label probability $|a|^2$ and phase-label-flip probability $|b|^2$ under a <Bell-basis measurement>. This follows because the local <Pauli operator> maps the two orthogonal components into the two Bell states whose phase label differs. The resource is a coherent <pure state>, even though its measured label statistics form a classical noisy channel.
Back to article page
