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Chinese Physics C

Probing quantum phase transitions in the sdg -Interacting Boson Model using von neumann entropy

Maryam Ghapanvari, M Sayedi, Narjes Amiri, M. A. Jafarizadeh

Published Jun 2, 2026• 0 citations
Publisher

Abstract

Abstract In this work, the von Neumann entropy has been calculated and employed as a probe to analyse quantum phase transitions (QPTs) within the -Interacting Boson Model ( -IBM). The von Neumann entropy between the -boson and -boson sectors is used as an indicator of QPTs and as a robust observable for the theoretical analysis of the isotopes. The von Neumann entropy correctly characterises the QPT in the transition region. The numerical results show that the and isotopes are located in the and limits, respectively.

DOI
10.1088/1674-1137/ae75fc

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Abstract In this work, the von Neumann entropy has been calculated and employed as a probe to analyse quantum phase transitions (QPTs) within the -Interacting Boson Model ( -IBM). The von Neumann entropy between the -boson and -boson sectors is used as an indicator of QPTs and as a robust observable for the theoretical analysis of the isotopes. The von Neumann entropy correctly characterises the QPT in the transition region. The numerical results show that the and isotopes are located in the and limits, respectively.
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Analysis of the U(5)↔SU(3)U(5)\leftrightarrow SU(3)U(5)↔SU(3) transitional region from an entanglement-based perspective
The degree of entanglement between components of a bipartite system can serve as a useful criterion for studying Quantum Phase Transitions (QPT). The von Neumann entropy and generalized concurrence serve as measures, while Schmidt number and Schmidt gap are quantifiers; together, they are key tools for identifying QPT. Using these tools, we have examined the QPT in the [Formula: see text] region within the first version of the semiclassical approximation of the Interacting Boson Model (IBM-1). Additionally, the Kullback-Leibler divergence (KLD) was employed as a criterion to compare two probability distribution functions in order to identify the transition region and the critical point. The theoretical results indicated that the Schmidt number and Schmidt gap, the von Neumann entropy, generalized concurrence, and the KLD can characterize the transition behavior and critical point (X(5)) in this region. To verify these results in real nuclei, the Dysprosium isotopic chain was selected. Using the suggested entanglement measures, the symmetry limits and the critical point were identified. The results obtained are fully consistent with experimental evidence.
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Quantum phase transitions (QPTs) in odd-mass Nb isotopes are investigated in the framework of the interacting boson-fermion model with configuration mixing. A quantum analysis reveals a Type I QPT (gradual shape-evolution within the intruder configuration) superimposed on a Type II QPT (abrupt crossing of normal and intruder states), thus demonstrating the occurrence of intertwined QPTs. A classical analysis highlights the implications for the single particle motion in the deformed field generated by the even-even Zr cores.
We propose a new approach to study quantum phase transitions in low-dimensional lattice models. It is based on studying the von Neumann entropy of two neighboring central sites in a long chain. It is demonstrated that the procedure works equally well for fermionic and spin models, and the two-site entropy is a better indicator of quantum phase transition than calculating gaps, order parameters, or the single-site entropy. The method is especially convenient when the density-matrix renormalization-group algorithm is used.