Quantum phase transitions and information-theoretic measures of a spin-oscillator system with non-Hermitian coupling
- URL: http://arxiv.org/abs/2506.23356v1
- Date: Sun, 29 Jun 2025 18:24:20 GMT
- Title: Quantum phase transitions and information-theoretic measures of a spin-oscillator system with non-Hermitian coupling
- Authors: Gargi Das, Aritra Ghosh, Bhabani Prasad Mandal,
- Abstract summary: We analytically compute some information-theoretic measures for a spin-oscillator system with non-Hermitian coupling.<n>We expose the appearance of exceptional points (EP) on such two-dimensional subspaces together with quantum phase transitions marking the transit from real to complex eigenvalues.
- Score: 6.412262542272846
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: In this paper, we describe some interesting properties of a spin-oscillator system with non-Hermitian coupling. As shown earlier, the Hilbert space of this problem can be described by infinitely-many closed two-dimensional invariant subspaces together with the global ground state. We expose the appearance of exceptional points (EP) on such two-dimensional subspaces together with quantum phase transitions marking the transit from real to complex eigenvalues. We analytically compute some information-theoretic measures for this intriguing system, namely, the thermal entropy as well as the von Neumann and R\'enyi entropies using the framework of the so-called \(G\)-inner product. Such entropic measures are verified to be non-analytic at the points which mark the quantum phase transitions on the space of parameters -- a naive comparison with Ehrenfest's classification of phase transitions then suggests that these transitions are of the first order as the first derivatives of the entropies are discontinuous across such transitions.
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