https://doi.org/10.1140/epjc/s10052-024-13678-6
Regular Article - Theoretical Physics
Thermalization and non-monotonic entanglement growth in an exactly solvable model
1
Center for Quantum Mathematics and Physics (QMAP), Department of Physics, University of California, 95616, Davis, CA, USA
2
Department of Physics, Tezpur University, 784028, Tezpur, Assam, India
Received:
11
September
2024
Accepted:
2
December
2024
Published online:
19
December
2024
We study quantum quenches and subsequent non-equilibrium dynamics of free Dirac fermions in 1 + 1 spacetime dimensions using time dependent mass. The final state is a normalized boundary state which is called generalized Calabrese-Cardy (gCC) state and the system thermalizes to a generalized Gibb’s Ensemble(GGE). We can also tune the initial states so that the final states are exact Calabrese-Cardy (CC) state and special gCC states. The system in the CC state thermalizes to a Gibb’s ensemble. We derive closed-form analytic expressions for the growth of entanglement entropy of subsystems consisting of arbitrary number of disjoint intervals in CC state. We show that the entanglement entropy of a single interval grows monotonically before saturation. In case of certain gCC states, for particular charges, the entanglement entropy of a single interval grows non-monotonically when the effective chemical potential is increased beyond a critical value. We argue that the non-monotonic growth of entanglement entropy is a boundary effect which arises due to increase in long range correlation and decrease in short range correlation at early times.
© The Author(s) 2024
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