= Operation fidelity
{title2=$F_{\rm op}(\Lambda,\rho)=\sqrt{F_e(\rho,\Lambda)}$}
In the unsquared <quantum fidelity> convention, operation fidelity compares a <purification of a density operator> with its image under a <quantum channel> acting on the source subsystem:
$$
F_{\rm op}(\Lambda,\rho)=F\bigl(|\Psi_\rho\rangle\langle\Psi_\rho|,(\operatorname{id}\otimes\Lambda)(|\Psi_\rho\rangle\langle\Psi_\rho|)\bigr).
$$
Its square is <entanglement fidelity>. Thus this convention is distinct from the squared quantity $F_e$; the two should not be installed as synonyms.
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