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From thermal to excited-state quantum phase transition: The Dicke model
1Departamento de Física Aplicada III, Escuela Técnica Superior de Ingeniería, Universidad de Sevilla, Sevilla, Spain.
Physical Review. E
|January 20, 2018
Summary
This study explores the Dicke model
Area of Science:
- Quantum thermodynamics
- Statistical mechanics
Background:
- The Dicke model describes light-matter interaction.
- Understanding its thermodynamic properties is crucial for quantum technologies.
Purpose of the Study:
- To investigate the thermodynamics of the full Dicke model across all angular momentum sectors.
- To analyze both excited-state quantum phase transitions and thermal phase transitions.
Main Methods:
- Thermodynamic analysis using both microcanonical and canonical ensembles.
- Examination of the full spectrum including all angular momentum sectors (j).
Main Results:
- In the canonical ensemble, parity symmetry breaks spontaneously at the critical temperature.
- In the microcanonical ensemble, a critical energy divides the spectrum, defining regions of parity symmetry behavior.
- Logarithmic singularities of excited-state quantum phase transitions are absent in the full model.
Conclusions:
- The full Dicke model exhibits distinct thermodynamic behaviors depending on the ensemble.
- Parity symmetry plays a critical role in both canonical and microcanonical descriptions.
- The study clarifies the nature of phase transitions in the comprehensive Dicke model.
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