Southeast University Team Identifies Extremal Bethe Solutions for Minimal Entanglement

Yu Hao and colleagues at Southeast University, in collaboration with Chinese Academy of Sciences and The non-compact SL, have analysed the quantum entanglement of Bethe states within integrable spin chains. This includes the XXX½ model and its variations, as well as the non-compact SL(2, ) chain, to understand entanglement properties in these systems. A detailed analysis of bipartite entanglement entropy across the spectrum of finite chains identified Bethe solutions that either minimise or maximise entanglement. Minimal entanglement does not always correspond to the ground state in higher-spin models, a departure from the behaviour observed in the antiferromagnetic XXX½ chain. Unique entanglement features were revealed in the non-compact SL(2, ) chain. An algorithm was developed to explore the maximum possible entanglement achievable by Bethe states, offering new insights into…