Design and Characterization of Microwave Packages for Superconducting Qubits*

Solid-state qubits with transition frequencies in the microwave regime, such as superconducting qubits, are at the forefront towards the realization of practical quantum processors. However, the high-fidelity and simultaneous control over these qubits remains a challenge in achieving quantum computation at scale. Multiple, often interrelated factors such as spurious modes, conduction losses, and crosstalk impose challenges that require a comprehensive approach to package design. Here, we provide an overview of our recent work aimed at systematically addressing these challenges, including mode suppression, chip-to-board interconnect design, interposer design, and material choices. We present results from simulations and demonstrate the corresponding physical characterization of the electromagnetic environment of the qubit.