Answer by Rammus for Quantum relative entropy with respect to a pure state
I'd like to add to Angelo Lucia's answer slightly. It is not very surprising that $S(\rho \| \sigma)$ can take the value $+\infty$ once we realise that the relative entropy is a generalization of the...
View ArticleAnswer by Angelo Lucia for Quantum relative entropy with respect to a pure state
If $\sigma$ is not full rank, then the correct way to interpret the quantum relative entropy formula you wrote is to assign it the value of $+\infty$ when the support of $\rho$ is not included in the...
View ArticleQuantum relative entropy with respect to a pure state
I want to evalualte the quantum relative entropy $S(\rho|| \sigma)=-{\rm tr}(\rho {\rm log}(\sigma))-S(\rho)$, where $\sigma=|\Psi\rangle\langle\Psi|$ is a density matrix corresponding to a pure state...
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