Quantum Phase Transitions in the Interacting Boson Model: Integrability, level repulsion and level crossing

Abstract

We study the quantum phase transition mechanisms that arise in the Interacting Boson Model. We show that the second-order nature of the phase transition from U(5) to O(6) may be attributed to quantum integrability, whereas all the first-order phase transitions of the model are due to level repulsion with one singular point of level crossing. We propose a model Hamiltonian with a true first-order phase transition for finite systems due to level crossings.

Accepted in PRL

References in corpus (4)

• A Class of Exactly Solvable Pairing Models
• Wave-function entropy and dynamical-symmetry breaking in the interacting boson model
• The Origin of Degeneracies and Crossings in the 1d Hubbard Model
• New mechanism for the enhancement of $sd$ dominance in interacting boson models

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• Phase transitions with finite atom number in the Dicke Model
• Correlation and entanglement of two-component Bose-Einstein condensates in a double well
• To what extent does the self-consistent mean-field exist?