>I am in the camp that believes that quantum computing is not possible in any useful sense; in particular a quantum computer will not be capable of being significantly more powerful than a classical computer, in the quantum supremacy sense.
Could you elaborate on that? I was under the impression that some companies are using Quantum Computers because quantum supremacy has been demonstrated (such as in molecular modeling for drug discovery or materials science) - but I'm a complete novice here, and would love to learn more. I'm probably quite wrong, and happy to be corrected.
Also, by not possible in a useful sense, do you mean that QCs as they are now versus in N years, or just in general?
When I say that quantum computing is not possible, I mean in general. It's a dead end. Note that this belief is subject to being falsified by progress in the field or a demonstration of error correction at scale.
There are companies selling and companies using "Quantum Computers". For example, D-Wave systems sells a computer that uses quantum annealing so solve a class of minimization problems.
To date, there is no quantum computer, in a commercial or a research setting, that has demonstrated it can compute anything faster than a classical computer (this includes the D-Wave systems).
The current trend is to try to establish quantum supremacy (and thus falsify the error correction is impossible thesis) through building extremely simple (non-general purpose) quantum systems. Most recently Google announced a successful attempt that has since been invalidated.
There are no quantum computers in practical use at the moment. This essay^ by IBM (incredibly biased towards making quantum computing seem useful) provides many "visions of"'s and "potential to"'s and "may benefit"'s, but nothing in the present tense.
Could you elaborate on that? I was under the impression that some companies are using Quantum Computers because quantum supremacy has been demonstrated (such as in molecular modeling for drug discovery or materials science) - but I'm a complete novice here, and would love to learn more. I'm probably quite wrong, and happy to be corrected.
Also, by not possible in a useful sense, do you mean that QCs as they are now versus in N years, or just in general?