Funny you should ask, because I have always noted that since the transistor, all our computational devices are rooted in QM, meaning that their design and fabrication is all according to quantum theory.
The so called quantum computer claims to use the parameters of quantum theory itself, that is quantum "amplitudes", as the parameters in the computational algorithm, and this is something altogether different.
In this sense the quantum computer is an ANALOG computer. ANALOG, in its original sense means that the computational device emulates the laws governing the problem being solved, and I believe this holds true for these putative quantum computers. They do not represent an alternative to digital computation as we practice it.
Mu understanding of it, extremely limited as it is as I am no physicist, is that the traditional analog/digital computer deals (in a sense) in fact. Binary 1/0.
Quantum computers (QC) deals in probabilities. Every ‘thing’ per se, has a wave in the probability field of possibilities. Of which there are an infinite number. Each of those ‘things’ is a possible reality. The Schrodinger’s cat thing. It’s alive AND dead until someone observes it, the probability wave collapses and the probability becomes ‘real’ IE, comes into existence.
Among these infinite of possible states, other factors/states of other possibilities interact and effect each other. As such, some things become more possible than others/their probability wave will ‘collapse’ and they become real/true/factual.
Confusing? Yup. Fascinating stuff to ponder though. The pop sci books by Kip Thorne and Michu Kaiku make some sense of it all for the non genius though. Well as much ‘sense’ as one can make I guess. All of this is about 3 multiverses away from conventional thinking.