Engineering the environment of superconducting quantum processors with multilayer PCBs

Precise and accurate coherent control of qubits is critical to the success of superconducting quantum computing. Microwave crosstalk is a ubiquitous problem for large scale superconducting quantum processors and poses a challenge to scaling up few-qubit coherent control results. Although crosstalk is classical, deterministic, and can be mitigated to some degree with electromagnetic nulling, the frequency dependence of crosstalk and significant calibration overhead for compensation schemes motivate hardware solutions. 3D integration techniques such as through silicon vias and bump bonds offer a solution at the cost of fabrication complexity. We propose and present initial experiments on a crosstalk mitigation scheme using commercial multilayer printed circuit boards (PCBs) to enable rapid turnaround and widespread adoption.