Efficient two-qutrit gates in superconducting circuits using parametric coupling

TL;DR

This paper proposes a fast, scalable method for implementing two-qutrit controlled-Z gates in superconducting circuits using parametric coupling, improving fidelity and speed over existing techniques.

Contribution

The authors introduce a protocol utilizing parametric coupling and partial state swaps to realize efficient two-qutrit gates in superconducting circuits.

Findings

Protocol enables fast two-qutrit gates with high fidelity.

Uses flux-tunable transmon for controlled parametric coupling.

Potential for scalable quantum computing architectures.

Abstract

Recently, significant progress has been made in the demonstration of single qutrit and coupled qutrit gates with superconducting circuits. Coupled qutrit gates have significantly lower fidelity than single qutrit gates, owing to long implementation times. We present a protocol to implement the CZ universal gate for two qutrits based on a decomposition involving two partial state swaps and local operations. The partial state swaps can be implemented effectively using parametric coupling, which is fast and has the advantage of frequency selectivity. We perform a detailed analysis of this protocol in a system consisting of two fixed-frequency transmons coupled by a flux-tunable transmon. The application of an AC flux in the tunable transmon controls the parametric gates. This protocol has the potential to lead to fast and scalable two-qutrit gates in superconducting circuit architectures.