Page curve and symmetries

A bstract Motivated by the quantum process of black hole evaporation and its implications for symmetries, we consider a qubit system with random dynamics as toy model hole. We compute symmetry-resolved entropies discuss implications. first case where charges are conserved entropies. derive analogue Page curve. then symmetry is explicitly broken no longer conserved. It serves global breaking in evaporation. Despite simple framework, capture various interesting features during analogous our model.