IEEE Spectrum mag, the leading journal for electrical engineers, published an article on The Case Against Quantum Computing:
Quantum computing is all the rage. It seems like hardly a day goes by without some news outlet describing the extraordinary things this technology promises. Most commentators forget, or just gloss over, the fact that people have been working on quantum computing for decades — and without any practical results to show for it. ...There are comments here.
On the hardware front, advanced research is under way, with a 49-qubit chip (Intel), a 50-qubit chip (IBM), and a 72-qubit chip (Google) having recently been fabricated and studied. The eventual outcome of this activity is not entirely clear, especially because these companies have not revealed the details of their work.
While I believe that such experimental research is beneficial and may lead to a better understanding of complicated quantum systems, I’m skeptical that these efforts will ever result in a practical quantum computer. Such a computer would have to be able to manipulate — on a microscopic level and with enormous precision — a physical system characterized by an unimaginably huge set of parameters, each of which can take on a continuous range of values. Could we ever learn to control the more than 10300 continuously variable parameters defining the quantum state of such a system?
My answer is simple. No, never.
IBM and Google were claiming in 2017 that they would have demonstrated quantum supremacy before the end of that year. Now we are almost at the end of 2018, and still no quantum supremacy.
It is rare for a mainstream publication to admit that quantum computing may be impossible. The author is a well-respected physicist.