Local quantum quenches in critical one-dimensional systems: entanglement, the Loschmidt echo, and light-cone effects

Understand

We study a particular type of local quench in a generic quantum critical one-dimensional system, using conformal field theory (CFT) techniques, and providing numerical checks of the results in free fermion systems.

• The system is initially cut into two subsystems $A$ and $B$ which are glued together at time $t=0$.
• We study the entanglement entropy (EE) between the two parts $A$ and $B$, using previous results by Calabrese and Cardy, and further extending them.
• We also study in detail the (logarithmic) Loschmidt echo (LLE).