关键词: 熵, CPT内积, 纠缠, Bell态, PT对称性

Abstract: We studied the classical entanglement problem of four parity-time (PT) symmetric Bell states under Hermitian conditions. The results show that among
the four PT symmetric Bell states, |Φ_-〉 and |Ψ_-〉 are still classical quantum states, and are still maximally entangled states under Hermitian inner product; whereas |Φ₊〉 and |Ψ₊〉 are no longer always classical quantum states, and the classical quantum states normalized by Hermitian inner product are no longer always maximally entangled states under Hermitian inner product.

Key words: entanglement, CPT inner product, entropy, PT symmetry, Bell state