Well all those temperature profiles go out the window once you step away from planar silicon architectures.
With all the, slightly ahead of our time, technology already deployed in the QC-verse I do not find it all that hard to believe that the core technology.
Think 3-5 materials, carbon nano tubes and Graphene, Q bits and electron spin control, positron circuits [still pure science fantasy - thanks Perry Rhodan].
Then there is such things as photonics where the circuitry uses light instead of electron flow, super conductivity and just plain ole planar stacking at the chip level.
< think club sandwich but with thinner insulating bread slices in the middle layers >