Questions tagged [entanglement-breaking-channels]

a class of stochastic maps, or channels, whose action (when tensored with the identity) on an entangled state always yields a separable state.

Filter by
Sorted by
Tagged with
2 votes
0 answers
51 views

How to write the joint action of a CP map that acts on a single qubit of a bipartite state?

The question Say I have a completely-positive (CP) map $\mathcal{A}_{ij}$ defined in terms of two projectors $\Pi_i = |i\rangle \langle i |$ and $\Pi_j = |j\rangle \langle j |$ that acts on a density ...
user avatar
  • 21
3 votes
1 answer
197 views

How can one check if a given quantum channel is unitary?

A unitary channel is a channel $\mathcal{U}$ of the following form: $\mathcal{U}(\rho) = U\rho U^{\dagger}$. A mixed unitary channel is a channel $\mathcal{U}_m$ of the form: $\mathcal{U}_m(\rho) = \...
user avatar
1 vote
1 answer
96 views

Are entanglement breaking channels of any use?

As the name suggests, an entanglement breaking channel $\Phi$ is such that $(Id \otimes \Phi)[\rho]$ is always separable, even when $\rho$ is entangled. Won't such channels be useless, as they destroy ...
user avatar
  • 243
2 votes
0 answers
91 views

A way to check if entanglement is increased or decreased

I was wondering if there is a way to check if the amount of entanglement is increased or decreased after a quantum operation without calculating the actual value. That is, it does not concern with the ...
user avatar
  • 21
2 votes
3 answers
264 views

Why are entanglement breaking channels, defined as $\Phi(\rho)=\sum_a \operatorname{Tr}(\mu(a)\rho)\sigma_a$, entanglement breaking?

Define an entanglement breaking channel $\Phi$ as a channel (CPTP map) of the form $$\Phi(\rho) = \sum_a \operatorname{Tr}(\mu(a)\rho) \sigma_a\tag A$$ for some POVM $\{\mu(a)\}_a$ and states $\...
user avatar
  • 19.1k