About That Perfect Clock…

Physicist proves impossibility of quantum time crystals

Bruno’s proof demonstrates that setting a system of particles in motion around a one-dimensional magnetic ring always increases the ground-state energy of the system so that it’s no longer in its ground state, which prohibits the existence of a rotating ground-state system. The proof covers systems rotating at any finite angular velocity.

I had linked to this some time back because the press release was bad and made some overly bold extrapolations. Interesting that a periodic system as described can’t be in a ground state.

There are also probably a couple of “I reject quantum theory” crackpots who will be disappointed, as this seems to rule out some of the favorite classical atom models. Oh, who am I kidding. They are impervious.