Coupler characterization of superconducting transmons qubits for cross-resonance gate

We characterize two-qubit cross-resonance gates and unintended residual coupling on various coupled qubit arrangements. Direct coupling versus coupling via a quantum bus are studied on the basis of cross-resonance gate rate and fall-off of non-nearest neighbor coupling. We experimentally extract coupling rates using Hamiltonian tomography methods, and compare with microwave simulations.