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Excited-state quantum phase transitions in the anharmonic Lipkin-Meshkov-Glick model: Dynamical aspects
J Khalouf-Rivera1,2, J Gamito3, F Pérez-Bernal2,4
1Departamento de Física Aplicada III, Escuela Técnica Superior de Ingeniería, Universidad de Sevilla, 41092 Sevilla, Spain.
Physical Review. E
|July 19, 2023
Summary
The study explores a new excited-state quantum phase transition (ESQPT) in the Lipkin-Meshkov-Glick model. This anharmonity-induced ESQPT shows dynamical effects similar to the standard model
Area of Science:
- Quantum Many-Body Physics
- Condensed Matter Theory
Background:
- The Lipkin-Meshkov-Glick (LMG) model exhibits ground-state and excited-state quantum phase transitions (QPTs).
- An anharmonic term introduces a second excited-state quantum phase transition (ESQPT), modifying static properties.
Purpose of the Study:
- To investigate the dynamical implications of the newly discovered anharmonity-induced ESQPT.
- To analyze the impact of this ESQPT on quantum quench dynamics.
Main Methods:
- A quantum quench protocol is applied to the modified LMG Hamiltonian.
- Analysis of time evolution of survival probability and local density of states.
- Calculation of Loschmidt echoes and microcanonical out-of-time-order correlators (OTOC).
Main Results:
- The anharmonity-induced ESQPT influences the dynamics after a quantum quench.
- Dynamical consequences of the new ESQPT mirror those of the pre-existing ESQPT in the standard LMG model.
- Specific impacts on survival probability, local density of states, Loschmidt echoes, and OTOC are detailed.
Conclusions:
- The new ESQPT, despite its distinct origin, shares dynamical behaviors with the standard LMG model's ESQPT.
- Quantum quench dynamics provide a sensitive probe for studying ESQPT phenomena.
- This work deepens the understanding of quantum phase transitions in interacting many-body systems.
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