I’m not a physicist but wanted to direct you to Preposterous Universe, where, in a new post called “There is no classical world,” Sean Carroll mentions an experiment showing definitively that even a macroscopic object—a mirror cooled to near absolute zero—behaves according to quantum rather than classical mechanics. That is, instead of remaining absolutely still, it vibrates at an amplitude of 0.000000000000001 meter, as predicted by QM. And they could measure that vibration! There’s a nice animated video that describes it clearly. You will want to see that.
The universe continues to astound me. I don’t understand quantum mechanics, but that puts me in good company.