A Compact, Extensible, and Flexible Cable Solution for Superconducting Qubit

As cryogenic quantum processors grow to larger qubit counts, the ability to efficiently route microwave signals into and out of a dilution refrigerator is quickly becoming a critical engineering challenge. The legacy approach to this routing leverages coaxial cable, which is optimal for crosstalk reduction and low-loss signal transmission but is intrinsically limited by connector size and cable fragility as cable radius decreases. Flex-printed cables, made from single- or multi-layer printed circuits on non-rigid substrates, offer the potential for low-crosstalk, high-density, physically robust cryogenic signal transfer. Here, we present a flex-print cable solution based on a stripline geometry as well as compact attenuator breakouts to ensure appropriate signal attenuation and thermalization. We demonstrate that the performance of qubits driven and measured via flex-print cable is not degraded relative to their performance when driven via standard coaxial cable.