Calibration of a cross-resonance two-qubit gate between directly coupled transmons

Journal article

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 stepwise reduction of dominant two-qubit coherent errors through mapping to microwave control parameters. We show experimentally that this procedure can enable a ZXˆ −π/2 gate with a fidelity F = 97.0(7)%, measured with interleaved randomized benchmarking. We show this in an architecture with out-of-plane control and readout that is readily extensible to larger-scale quantum circuits.

Authors: Patterson, A; Rahamim, J; Tsunoda, T; Spring, P; Jebari, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review Applied
• Volume: 12
• Issue: 6
• Article number: 064013
• Publication date: 2019-12-05
• Acceptance date: 2019-10-18
• DOI: 10.1103/PhysRevApplied.12.064013
• EISSN: 2331-7019
• Keywords: quant-ph