Autonomous characterization of multi-transmon circuit QED processors

Operating a modern circuit QED processor requires knowledge of the physical characteristics of a large number of interconnected qubits and resonators. These characteristics are initially learned through an extensive sequence of low-level measurements (e.g., spectroscopy). Such measurements must be repeated for every new device due to fabrication non-uniformity and design variation. We demonstrate autonomous device characterization starting from minimal prior knowledge such as device layout and design parameters (e.g., qubit and resonator frequencies and coupling strengths). Examples include qubit-resonator matching, finding qubit sweetspots, and identifying the linear regime for readout. This approach accelerates the transition to graph-based calibration of quantum operations (qubit gates and readout). During the characterization process, a digital twin is constructed based on the learned device parameters. This interactable model can also be used to simulate the low-level characterization of devices with perturbed parameters.