Cancellation of unwanted ZZ interactions for cross-resonance gates by superconducting qubit engineering*

Superconducting qubit architectures are susceptible to unwanted ZZ interactions that limit 2QB gate fidelities and introduce correlated errors. This unwanted ZZ interaction is especially harmful to the cross-resonance gate. In this talk, we augment the transmon-qubit architecture by introducing a new superconducting qubit similar to the transmon but with positive anharmonicity. We experimentally demonstrate how this new architecture allows the unwanted ZZ between two distinct qubits to be greatly reduced with respect to typical values for transmon-only devices, and how this can be further leveraged to achieve high fidelity gates. We discuss design considerations and show how this approach can be integrated for designing a large-scale device with reduced ZZ between all pairs of nearest neighbors qubits and negligible spectator-qubit effects.