QM is quite simple. But then we also have QFT. The difficult things you were talking about fall more on the QFT side of things. In my view QM predicts QC will

QM is quite simple. But then we also have QFT. The difficult things you were talking about fall more on the QFT side of things. In my view QM predicts QC will work just like math predicts Turing machines will work. But the practical realization of an advanced Turing machine can indeed be a very complicated thing - in fact we need quantum physics to understand how modern transistors work. So if practical useful QC don't work, wouldn't that be more of a QFT engineering problem? I fully agree that we might not be able to build a working QC, just like we are struggling with fusion power for over 50 years now despite theory predicting it should work, and in theory it being a simpler problem than QCs. Maybe I'm being pedantic with the distinction between QM/QFT...