Quantum Matter Seminar

The Page curve was first discussed in black hole physics where is describes the entanglement dynamics between the black hole and Hawking radiation: After an initial linear growth of the entanglement entropy as derived by Hawking in 1975, unitarity requires downbending of the entanglement curve at the Page time. This downbending is missing in Hawking's semiclassical calculation and has been at the center of the black hole information paradox ever since. Motivated by this unusual behavior of the entanglement entropy I introduce a simple exactly solvable model of a quantum many-body system coupled to a non-interacting environment which shows a Page curve. After the equivalent of the Page time the dynamics of this model is quite intriguing for an observer who only has access to the environment: Adding particles to the state in the environment makes the environment state purer and its energy variance smaller. This behavior is generic for a whole class of similar models.