Silicon is made out of atoms, which also have quantum effects, and we actually rely on these effects to design transistors. Quantum mechanics has been around for 100 years. What's impossible to simulate?

This is a bit glibly wrong.

That we understand there are certain quantum effects at play already does not mean we understand them to the degree necessary to control them.

We do not understand quantum effects to the degree necessary in order to 'simulate' anything down to a certain level.

Moreover, even if we could, it would have nothing to do with understanding the computational nature of 'the mind'.