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Published on: June 7, 2018
Quantum fidelity and thermal phase transitions
1Theoretical Division, MS B213, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Summary
Quantum fidelity effectively identifies thermal phase transitions, especially lambda transitions. Variations of this method overcome limitations caused by thermal fluctuations at high temperatures.
Area of Science:
- Quantum physics
- Statistical mechanics
- Condensed matter theory
Background:
- Thermal phase transitions are crucial in understanding matter's behavior at different temperatures.
- Quantum fidelity offers a sensitive measure to detect changes in quantum states.
Purpose of the Study:
- To investigate the utility of quantum fidelity for characterizing second-order thermal phase transitions.
- To analyze the impact of temperature perturbations on mixed-state fidelity.
- To adapt fidelity approaches for improved analysis of thermal phase transitions.
Main Methods:
- Analyzing mixed-state fidelity under temperature perturbations.
- Examining fidelity behavior in lambda transitions and other second-order phase transitions.
- Connecting fidelity with thermodynamic quantities.
Main Results:
- Quantum fidelity is more effective for lambda transitions (divergent second free energy derivatives).
- Fidelity's sensitivity decreases at high temperatures due to thermal fluctuations.
- Proposed fidelity variations enhance analysis in challenging temperature regimes.
Conclusions:
- Quantum fidelity is a robust tool for detecting thermal phase transitions.
- The study provides an improved fidelity-based method for analyzing phase diagrams, demonstrated on the Lipkin-Meshkov-Glick model.
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