I've previously described quantum computing as being in its "ENIAC" phase, an analogy that would put effective quantum computing several decades away, at best. After all, it took seven decades for binary computers to get from ENIAC to Android, and there was no reason to suspect that quantum computers would any easier to develop than their binary predecessors.
According to a long article on IEEE.org, penned by Mikhail Dyakonov, who does research in theoretical physics professionally, that decades-away estimate might actually be too optimistic. Quantum computers, he argues, might be more than merely difficult to develop, but impossible.
One of the earliest electronic general-purpose computers ever made, the Electronic Numerical Integrator and Computer (or, ENIAC) was a monster of a machine. Brought online in 1946, ENIAC eventually grew to include 17,468 vacuum tubes, 7200 crystal diodes, 1500 relays, 70,000 resistors, 10,000 capacitors and approximately 5,000,000 hand-soldered joints. It weighed over 27 tonnes, consumed 150 kW of electricity, ran programs from punch cards (a huge leap forward from earlier models of computer), cost 6.1 million inflation-adjusted US dollars, and had roughly the computational power of a scientific calculator.
It's now 71 years later, and today's personal computing technology bears very little resemblance to ENIAC. A modern smartphone can weigh as little as 155 g (5.47 oz, or 0.00000574% of ENIAC), yet packs 1300 times ENIAC's computing power into that tiny package. Compared to today's computing technology, ENIAC is a dinosaur, and it would be virtually useless for any modern computing application, but ENIAC is also the start of the modern computer era; something like ENIAC must first exist, in order for our modern information age to be possible.
Knowing this, I have to admit that it gave me something of a frisson to see what the current state of quantum computing looks like, courtesy of Linus Tech Tips: