Yeah, that’s more than a few particles. If you had a planet-sized computer, you could still simulate a block of ice, although it might still be hard to explain in a bird-eye view kind of way why the simulated ice is slippery. Which is what this paper is actually trying to do.

Ditto for superconductors. It’s true that closer to absolute zero something is, the longer quantum features stay relevant, and that imposes a pretty punishing penalty. It’s not infinite, though.