Quantum entanglement in the Sachdev-Ye-Kitaev model and its generalizations

Entanglement is one of the most important concepts in quantum physics. We review recent progress in understanding the quantum entanglement in many-body systems using large- solvable models: the Sachdev-Ye-Kitaev (SYK) model and its generalizations. We present the study of entanglement entropy in the original SYK model using three different approaches: the exact diagonalization, the eigenstate thermalization hypothesis, and the path-integral representation. For coupled SYK models, the entanglement entropy shows linear growth and saturation at the thermal value. The saturation is related to replica wormholes in gravity. Finally, we consider the steady-state entanglement entropy of quantum many-body systems under repeated measurements. The traditional symmetry breaking in the enlarged replica space leads to the measurement-induced entanglement phase transition.

Automated summary

Entanglement is a crucial concept in quantum physics. Recent progress in understanding quantum entanglement in many-body systems using large-solvable models, such as the Sachdev-Ye-Kitaev (SYK) model and its generalizations, has been reviewed. The study of entanglement entropy in the original SYK model using three different approaches has been presented. For coupled SYK models, the entanglement entropy exhibits linear growth and saturation at the thermal value, which is related to replica wormholes in gravity. Additionally, the measurement-induced entanglement phase transition in quantum many-body systems under repeated measurements has been discussed.