Summary: We study the Landau-Streater quantum channel \({\Phi} : \mathcal{B(H}_d) \mapsto \mathcal{B(H}_d)\), whose Kraus operators are proportional to the irreducible unitary representation of \(\operatorname{SU}(2)\) generators of dimension \(d\). We establish \(\operatorname{SU}(2)\) covariance for all \(d\) and \(\operatorname{U}(3)\) covariance for \(d=3\). Using the theory of angular momentum, we explicitly find the spectrum and the minimal output entropy of \(\Phi\). Negative eigenvalues in the spectrum of \(\Phi\) indicate that the channel cannot be obtained as a result of Hermitian Markovian quantum dynamics. Degradability and antidegradability of the Landau-Streater channel is fully analyzed. We calculate classical and entanglement-assisted capacities of \(\Phi\). Quantum capacity of \(\Phi\) vanishes if \(d=2, 3\) and is strictly positive if \(d\geq 4\). We show that the channel \(\Phi\otimes\Phi\) does not annihilate entanglement and preserves entanglement of some states with Schmidt rank 2 if \(d\geq 3\).{
©2019 American Institute of Physics}