What is "information" in physics?

In the sense you are asking: knowledge of any kind sent from one location in space-time to another location. The key concept is knowledge. The quantum state of an entangled particle is not information because it carries no knowledge. If I have one of a pair of entangled particles I have no control over the quantum state of the particle. Thus, I cannot change the quantum state of my particle to let you know that I just got up. You cannot look at your particle and have knowledge if I am awake or still sleeping