Characterization of Parametric Entangling Gates on a Multi-Qubit Quantum Processor*

Two-qubit gates activated via a parametrically driven, flux-tunable coupler are a promising approach to engineering fast, high-fidelity entanglement without the potential sacrifice in qubit coherence that comes with a fully tunable architecture. Flux-modulated couplers can also enable a universal hardware-native gateset — an invaluable resource for reducing circuit depth and improving algorithm performance on noisy intermediate scale quantum (NISQ) devices. However, realizing a coherence-limited gate fidelity remains a challenge. In this work, we experimentally investigate the sources of coherent error that limit the parametric gate fidelity in a multi-qubit device. Through identifying these error mechanisms, we explore a physically motivated, systematic approach to calibrating a continuous hardware-native gateset for efficient near-term algorithms.