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Phase transitions at high energy vindicate negative microcanonical temperature.
P Buonsante1, R Franzosi1, A Smerzi1
1QSTAR & CNR-Istituto Nazionale di Ottica, Largo Enrico Fermi 2, I-50125 Firenze, Italy.
Physical Review. E
|June 17, 2017
Summary
Negative absolute temperature is validated by Boltzmann entropy, enabling the study of phase transitions in systems with bounded energy. This contrasts with Gibbs entropy, offering new insights into nonlinear lattice models and ultracold gases.
Area of Science:
- Thermodynamics
- Statistical Mechanics
- Condensed Matter Physics
Background:
- The concept of negative absolute temperature arises from Boltzmann's microcanonical entropy definition for systems with bounded energy.
- Recent challenges questioned the validity of Boltzmann entropy, favoring Gibbs entropy for consistent thermodynamics.
Purpose of the Study:
- To provide evidence for the consistency of Boltzmann microcanonical entropy for both positive and negative temperatures.
- To demonstrate the capability of Boltzmann temperature in describing phase transitions at high energy densities.
Main Methods:
- Analytical derivations.
- Numerical simulations.
- Application to nonlinear lattice models.
Main Results:
- Boltzmann microcanonical entropy consistently describes systems with both positive and negative temperatures.
- Negative Boltzmann temperature successfully describes phase transitions at high energy densities, unlike Gibbs temperature.
- The findings are applicable to nonlinear lattice models, including photonic lattices and ultracold gases.
Conclusions:
- Boltzmann entropy offers a consistent thermodynamic framework for negative temperatures.
- This framework is crucial for understanding phase transitions in specific physical systems like optical lattices.
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