Quantum computers can't exist
Quantum computers are an illusion similar to middle ages chemical processes that were claimed to transmute pigs ears into gold. They are something that people wish existed because if such a a physical device with such "perfect" properties could exist it would give people wished for unlimited knowledge.
The experiments and reports of progress are similar to experiments proving the existence of the ether in the late 19th century, There were anomalies and alternative explanations of experimental results were ignored, Eventually Einstein's special relativity showed that the ether did not exist - was an illusion.
The experiments and theories that builders of quantum believe is called Von Neumann MacLane quantum logic. Its main problem is that it replaces quantum behavior that is a strange interaction of waves and particles like nothing else with formal mathematics.
The quantum computer languages are just virtual machines with instructions that some people find attractive similar to the old APL programming language that had matrix operations as primitives or Matlab that has primitives good for doing algebra. The primitive operations are simulated by some computer language close to the underlying Von Neumann architecture. People now mostly use matrix operation libraries instead of APL because it is more efficient.
There is a long history of attempts to disprove quantum logic that have not been published because of an almost religious like believe in formal logic. Even famous philosopher of science and British Knight Karl Popper could not get his disproof published (try searching for "Popper and quantum logic"). Einstein student David Bohm sympathized with Popper by writing "My advice to you is Never entangle yourself with buzz saws, cobras, and Von Neumann's articles on physics."
The history is interesting because in the 1940s Einstein and Niels Bohr conversations with Von Neumann probably led to Von Neumann's computer architecture.
My reply is long because I am working on my quantum logic talk for some summer conferences in Europe.
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