Conditional-phase (cz) gates in transmons can be realized by flux pulsing computational states towards resonance with noncomputational ones. We present a 40 ns cz gate based on a bipolar flux pulse suppressing leakage (0.1%) by interference and approaching the speed limit set by exchange coupling. This pulse harnesses a built-in echo to enhance fidelity (99.1%) and is robust to long-timescale distortion in the flux-control line, ensuring repeatability. Numerical simulations matching experiment show that fidelity is limited by high-frequency dephasing and leakage by short-timescale distortion.

Original languageEnglish
Article number120502
Number of pages6
JournalPhysical Review Letters
Issue number12
Publication statusPublished - 2019

    Research areas

  • quantum benchmarking, quantum control, quantum gates, superconducting qubits

ID: 57485016