Qudit Dynamical Decoupling on a Superconducting Quantum Processor

TL;DR

This paper develops and experimentally verifies dynamical decoupling protocols for qudits on a superconducting processor, improving coherence and fidelity in multi-level quantum systems.

Contribution

It introduces novel DD protocols for qudits based on the Heisenberg-Weyl group and demonstrates their effectiveness on a superconducting transmon platform.

Findings

Single-qudit DD sequences decouple qutrits and ququarts from decoherence.

Two-qudit DD sequences suppress cross-Kerr couplings.

Significant fidelity improvement of time-evolved qutrit Bell states.

Abstract

Multi-level qudit systems are increasingly being explored as alternatives to traditional qubit systems due to their denser information storage and processing potential. However, qudits are more susceptible to decoherence than qubits due to increased loss channels, noise sensitivity, and crosstalk. To address these challenges, we develop protocols for dynamical decoupling (DD) of qudit systems based on the Heisenberg-Weyl group. We implement and experimentally verify these DD protocols on a superconducting transmon processor that supports qudit operation based on qutrits $(d=3)$ and ququarts $(d=4)$. Specifically, we demonstrate single-qudit DD sequences to decouple qutrits and ququarts from system-bath-induced decoherence. We also introduce two-qudit DD sequences designed to suppress the detrimental cross-Kerr couplings between coupled qudits. This allows us to demonstrate a significant improvement in the fidelity of time-evolved qutrit Bell states. Our results highlight the utility of leveraging DD to enable scalable qudit-based quantum computing.