Nuclear fusion is a reality, it already works in bombs and the stars, and there are real reactors outputting significant energy. Will we ever see a reactor that doesn't tear itself apart in a few hours and doesn't cost at least a thousand times as much as solar panels? Who knows. But the physics foundation is sound, the missing part is "just" engineering.

Quantum computing relies on the universe being based on non-classical computation principles. We still don't know if the universe has such properties or if the quantum mechanics we observe are simply the result of a more complicated classical model, which would inherently limit the theoretical capabilities of quantum computers.

But the theoretical part aside, quantum computing is just not really evolving. When I first heard about 50+ qbit quantum computers I though it was a sign of clear progress, but I think it is just mostly moving the goal post, the requirement that you have to do some sort of computation to call the device a computer just kind of slipped away. Better freezers have of course done their part, but that just isn't going to push us anywhere near useful.