Efficient two-qutrit gates in superconducting circuits using parametric coupling
Mahadevan Subramanian, Adrian Lupaşcu · Physical Review A · 2023
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.