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

2025/06/29 by Das, Gargi, Ghosh, Aritra, Mandal, Bhabani Prasad
#FOS: Physical sciences #Mathematical Physics (math-ph) #Quantum Physics (quant-ph)

paper · doi:10.48550/arxiv.2506.23356

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.

Citations

• Density matrices and entropy operator for non-Hermitian quantum mechanics
• A Class of Exactly Solvable Real and Complex PT Symmetric Reflectionless Potentials
• New scattering features of quaternionic point interaction in non-Hermitian quantum mechanics
• PT-symmetric quantum mechanics

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• PT-Symmetric Spin--Boson Model with a Continuous Bosonic Spectrum: Exceptional Points and Dynamics