Published January 9, 2024 | Version v1
Publication

Excited-state Quantum Phase Transitions in the Anharmonic Lipkin-Meshkov-Glick Model: Static Aspects

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Description

The basic Lipkin-Meshkov-Glick model displays a second-order ground-state quantum phase transition and an excited-state quantum phase transition (ESQPT). The inclusion of an anharmonic term in the Hamiltonian implies a second ESQPT of a different nature. We characterize this ESQPT using the mean field limit of the model. The alternative ESQPT, associated with the changes in the boundary of the finite Hilbert space of the system, can be properly described using the order parameter of the ground-state quantum phase transition, the energy gap between adjacent states, the participation ratio, and the quantum fidelity susceptibility.

Abstract

Ministerio de Ciencia e Innovación PID2019-104002GB-C21, PID2019104002GB-C22, PID2020-114687GB-I00

Abstract

European Commission. Fondo Europeo de Desarrollo Regional UHU-1262561, US-1380840

Abstract

Junta de Andalucía P20_01247

Abstract

Ministerio de Economia, Industria y Competitividad UNHU-15CE-2848

Additional details

Created:
January 12, 2024
Modified:
January 12, 2024