The behavior of entangled photons is governed by the principles of quantum mechanics, which can seem counterintuitive from a classical perspective. It is important to clarify a few points related to your question:
Decoherence: Decoherence refers to the loss of quantum coherence between particles or systems, typically due to interactions with their surrounding environment. While decoherence can occur for entangled particles, it does not necessarily happen simultaneously for both particles. The timing of decoherence depends on the specific details of the system and its interaction with the environment.
Entanglement and separability: Entanglement refers to a quantum correlation between particles, where their quantum states are linked in such a way that the state of one particle cannot be described independently of the other. The entangled photons can be widely separated in space, and their quantum states remain interconnected, regardless of the distance between them. This property is known as non-locality and is a characteristic of entanglement.
Time and entanglement: In quantum mechanics, time is not "stopped" for particles. However, the concept of simultaneity and causality can be different from classical physics. Entanglement does not imply that one particle can instantaneously affect the other over long distances, violating the speed of light. Any information or influence between entangled particles cannot be used to transmit information faster than the speed of light, as confirmed by experimental tests of Bell's inequalities.
It's worth noting that quantum mechanics is a highly complex and nuanced field, and understanding its intricacies often requires a detailed study. While classical intuitions may not always align with quantum phenomena, the predictions of quantum mechanics have been extensively tested and confirmed through experiments.