A high-fidelity, two-qubit cross-resonance gate using interference couplers

Improving two-qubit gate performance and suppressing crosstalk are major challenges for building fault-tolerant quantum computers. In this talk, we will discuss a novel, fixed-frequency, multi-element coupling architecture for transmon qubits. This architecture features enhanced J exchange interaction strength and intrinsic idle ZZ suppression. We observe no degradation of qubit coherence (T1,T2 > 100μs) and measure a J/ZZ ratio greater than 100. Using the cross-resonance interaction we demonstrate a novel 200ns single-pulse CNOT gate and measure a gate fidelity of 99.77% (2.3e-3 gate error) from interleaved randomized benchmarking.

*We acknowledge support for characterization and calibration from IARPA under Contract No. W911NF-16-0114.