Flex cable solutions for Superconducting Quantum Computing

In order to achieve a very large number of RF signal lines, on the order of 10$^3$-10$^4$, in a dilution refrigerator

it is generally desired to move away from the standard coaxial solutions from cost, complexity, and specific area considerations.

We present a flex-cable solution that encompasses the entire signal chain. Each cable has multiple channels and is connectorized

with high-density surface mount components. The thermal conductivity and resistivity of the cables at various stages is tailored

to comply with typical dilution refrigerator cooling capacities and signals they are dedicated to, respectively. More specifically,

superconducting cables with $T_c>4$~K are incorporated below the pulse-tube stage and we show that high critical currents below

the PT can be obtained with excellent RF hygiene of the system, including cross-talk, reflections, and IR performance.

Incorporation of components such as surface mount attenuators, current bias resistors, and other components in the signal

chain will be shown.