Most quantum computers need to be cooled to frigid temperatures or contained in space-like vacuum chambers. Using light to do the computation avoids both of those fates, but at a cost—how do you hold a light beam in your hand long enough to do the computation? There are many approaches, and now a team in Japan has created a light-based quantum machine that's capable of many different computations, and will be available on the cloud in 2025.
Quantum computing is nothing like fusion, it’s been working for 20 years, just at smaller scales.
A better comparison would be graphene. Graphene exists, we can make it, just not much of it. It won’t change everything until we can mass produce it.
Fusion just plain doesn’t work (for generating energy) in practice yet.
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