This paper talks about Gibbs states, i.e., thermal states. These are very specific states that naturally occur if the system is in thermal equilibrium. The oth

This paper talks about Gibbs states, i.e., thermal states. These are very specific states that naturally occur if the system is in thermal equilibrium. The other thing you talk about is true. If you have a system in quantum superposition, to measure it you need to entangle it with some macroscopic system. Macroscopic systems decohere very fast. This concept is well explained in excellent John Preskill's quantum computing lecture notes [1] Note that the system for which wavefunction collapses is not in equilibrium with the measurements equipment (otherwise it wouldn't be measured), so the claims of the paper do not apply to this case. [1] https://web.archive.org/web/20231005202201/http://theory.caltech.edu/~preskill/ph219/chap3_15.pdf https://web.archive.org/web/20231005202201/http://theory.cal...