This Scientific American video, shared by Aeon, is pretty good if you’re looking for a quick basic primer on quantum computing. It’s short, less than nine minutes. Although I do have a beef which I’ll discuss below.
The beef, which is pretty common with popular explanations of quantum computing, is it implies than on a measurement, the circuit of qubits will somehow collapse to the right answer. This always used to confuse me, because the physics is that the collapse is random (at least operationally). Done just as the video suggests, a quantum computer would be a very expensive system to produce random answers.
As often discussed by Scott Aaronson, these systems have to promote the right answer, to amplify the probability of it being the collapsed result, and suppress the probability of the wrong answers. It does this using quantum interference, canceling out the undesirable answers while amplifying the correct one.
Incidentally, getting an idea of how this manipulation of quantum effects works is what pushed me over the line toward wave function realism (at least to some degree). Until reading about quantum computing, I was fine with the idea that the wave function is just a mathematical tool that doesn’t describe actual reality. But this technology depends on the structure of the theory being right throughout the entire process. Holding on to anti-realism in this case just seemed increasing obdurate, at least to me.