Realization of the Werner-Holevo and Landau-Streater quantum channels for qutrits on quantum computers.

We implement the Landau-Streater and Werner-Holevo quantum channels for qutrits on IBM quantum computers. These quantum channels correspond to a specific interaction between a qutrit with its environment, which results in the globally unitarily covariant qutrit transformation violating the multiplicativity of the maximal p-norm. Our realization of such 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 exploit the standard quantum gates only, so the developed algorithm can be executed on 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 by comparing their action on different input states with theoretical predictions. The overall efficiency is quantified via the fidelity between the theoretical and experimental Choi states, with the latter being physically implemented on the 20-qubit computer.