Questions tagged [mixed-unitary-channels]

For questions about mixed-unitary channels.

3 questions
9
votes
1 answer

Can the Kraus decomposition always be chosen to be a statistical mixture of unitary evolutions?

If $\mathcal{E}$ is a CPTP map between hermitian operators on two Hilbert spaces, then we can find a set of operators $\{K_j\}_j$ such that $$\mathcal{E}(\rho)=\sum_j K_j\rho K_j^\dagger $$ in the same spirit as any density matrix $\rho$ can be…
6
votes
2 answers

Determining whether there exists an equivalent set of unitary Kraus operators

I have a CPTP quantum channel $\mathcal{E}$ that I've characterized by an operator sum representation $\{E_i\}$ for $i=1, \dots, m$ which acts on an input state like $$ \mathcal{E}(\rho) = \sum_{i=1}^m E_i \rho E_i^\dagger $$ with $\sum_i…
-1
votes
1 answer

how to mix (or time average) two density matrix?

Given two density matrix $\rho_1,\rho_2$ with the same size, how to get a mix state of the two matrix, $$ \rho = \frac12 (\rho_1+\rho_2)? $$ e.g. there are two quantum channel both of them have 4 qubits, with density matrix $\rho_1,\rho_2$. Now, we…