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

## TL;DR

This paper demonstrates the implementation of specific qutrit quantum channels, namely Werner-Holevo and Landau-Streater, on IBM quantum computers by embedding qutrits into two-qubit systems and using standard quantum gates.

## Contribution

The authors develop a universal algorithm to realize qutrit channels on quantum computers using standard gates, and validate it on multiple IBM quantum devices and simulators.

## Key findings

- Successful implementation of LS and WH channels on IBM quantum hardware.
- High fidelity between theoretical and experimental Choi states.
- Algorithm compatible with any quantum computer using standard gates.

## Abstract

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.