Calibration of the cross-resonance two-qubit gate between
directly-coupled transmons
Phys. Rev. Applied 12 064013-064013
Authors:
AD Patterson, J Rahamim, T Tsunoda, P Spring, S Jebari, K Ratter, M Mergenthaler, G Tancredi, B Vlastakis, M Esposito, PJ Leek
Abstract:
Quantum computation requires the precise control of the evolution of a
quantum system, typically through application of discrete quantum logic gates on a set of qubits. Here, we use the cross-resonance interaction to implement a gate between two superconducting transmon qubits with a direct static dispersive coupling. We demonstrate a practical calibration procedure for the optimization of the gate, combining continuous and repeated-gate Hamiltonian tomography with step-wise reduction of dominant two-qubit coherent errors through mapping to microwave control parameters. We show experimentally that this procedure can enable a $\hat{ZX}_{-\pi/2}$ gate with a fidelity $F=97.0(7)\%$, measured with interleaved randomized benchmarking. We show this in a architecture with out-of-plane control and readout that is readily extensible to larger scale quantum circuits.