Loschmidt echo, emerging dual unitarity and scaling of generalized temporal entropies after quenches to the critical point

Understand

We show how the Loschmidt echo of a product state after a quench to a conformal invariant critical point and its leading finite time corrections can be predicted by using conformal field theories (CFT).

• We check such predictions with tensor networks, finding excellent agreement.
• As a result, we can use the Loschmidt echo to extract the universal information of the underlying CFT including the central charge, the operator content, and its generalized temporal entropies.
• We are also able to predict and confirm an emerging dual-unitarity of the evolution at late times, since the spatial transfer matrix operator that evolves the system in space becomes unitary in such limit.