Euclidean Wormholes and Gravitational States

Euclidean wormholes are known to encode important non-perturbative effects in the physics of quantum black holes. In this paper, we discuss the slicing of Euclidean wormholes along a time-reflection symmetric slice which treats half of the Euclidean geometry as a gravitational machinery to produce a semi-classical state. This type of state preparation is different from Hartle-Hawking states prepared with the CFT path integral, such as the thermofield-double state. Nevertheless, the two different types of states have order one overlaps provided the gravitational data agrees on the initial data slice. This raises an interesting puzzle: one can easily construct an infinite family of semi-classical states that have order one overlap with the thermofield double state, while having a very different Euclidean preparation. We provide a microscopic description of wormhole states in the dual CFT and reformulate the factorization puzzle in the language of entanglement and the Hilbert space.