Superposition does not fork the world. This common misconception arises due to confusion between superposition and the many-worlds interpretation of quantum mechanics, but it’s easy to see that the two are only superficially similar. States in a superposition still interfere—that's the essence of the double-slit experiment.
In contrast, when arguing that the timeline 'splits' due to measurements, the resulting universes do not interact at all and remain completely unaware of each other—they can never even know if the others exist.
If quantum computers truly 'forked' the world, they would be equivalent to non-deterministic Turing machines (capable of solving NP-complete problems in polynomial time), but quantum computing experts agree that they can still be modeled as deterministic Turing machines.
It's better to think of quantum computers as a type of analog computer, capable of solving certain problems that fit their model well, but not generally more powerful. It’s like an Intel CPU having SIMD or AVX instructions that allow it to perform certain operations faster, but these don't fundamentally change its capabilities. The no-free-lunch theorem applies.
In contrast, when arguing that the timeline 'splits' due to measurements, the resulting universes do not interact at all and remain completely unaware of each other—they can never even know if the others exist.
If quantum computers truly 'forked' the world, they would be equivalent to non-deterministic Turing machines (capable of solving NP-complete problems in polynomial time), but quantum computing experts agree that they can still be modeled as deterministic Turing machines.
It's better to think of quantum computers as a type of analog computer, capable of solving certain problems that fit their model well, but not generally more powerful. It’s like an Intel CPU having SIMD or AVX instructions that allow it to perform certain operations faster, but these don't fundamentally change its capabilities. The no-free-lunch theorem applies.