  We give a quantum circuit interpretation of evaporating black hole geometry.
We make an analogy between the appearance of island for evaporating black hole
and the transition from two-sided to one-sided black hole in the familiar
example of perturbed thermofield double. If Alice perturbs thermofield double
and waits for scrambling time, she will have a one-sided black hole with
interior of her own. We argue that by similar mechanism the radiation gets
access to the interior (island forms) after Page time. The growth of the island
happens as a result of the constant transitions from two-sided to one-sided
black holes.
