Quantum phase transitions and entanglement entropy in a non-Hermitian spin-boson system

• URL: http://arxiv.org/abs/2506.23356v2
• Date: Tue, 28 Oct 2025 17:22:42 GMT
• Title: Quantum phase transitions and entanglement entropy in a non-Hermitian spin-boson system
• Authors: Gargi Das, Aritra Ghosh, Bhabani Prasad Mandal,
• Abstract summary: We describe some interesting properties of a spin-boson system with non-Hermitian coupling.<n>We compute the spin-boson entanglement entropy on each invariant subspace to show that the two phases can be distinguished by their distinct entanglement-entropy profiles.
• Score: 3.4532054548640247
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: In this paper, we describe some interesting properties of a spin-boson system with non-Hermitian coupling. For this particular model, it is known that the Hilbert space can be described by infinitely-many two-dimensional invariant (closed) subspaces, together with the global ground state. We expose the appearance of exceptional points on such two-dimensional subspaces, together with quantum phase transitions marking the transition from real to complex eigenvalues. We also compute the spin-boson entanglement entropy on each invariant subspace to show that the two phases can be distinguished by their distinct entanglement-entropy profiles.

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