Realization of the Werner-Holevo and Landau-Streater quantum channels
  for qutrits on quantum computers
We realize Landau-Streater (LS) and Werner-Holevo (WH) quantum channels for
qutrits on the IBM quantum computers. These channels correspond to interaction
between the qutrit and its environment that result in the globally unitarily
covariant qutrit transformation violating multiplicativity of the maximal
$p$-norm. Our realization of LS and WH channels is based on embedding qutrit
states into states of two qubits and using single-qubit and two-qubit CNOT
gates to implement the specific interaction. We employ the standard quantum
gates hence the developed algorithm suits any quantum computer. We run our
algorithm on a 5-qubit and a 20-qubit computer as well as on a simulator. We
quantify the quality of the implemented channels comparing their action on
different input states with theoretical predictions. The overall efficiency is
quantified by fidelity between the theoretical and experimental Choi states
implemented on the 20-qubit computer.
A. I. Pakhomchik I. Feshchenko A. Glatz V. M. Vinokur A. V. Lebedev K. V. Kuzhamuratova S. N. Filippov G. B. Lesovik