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Updated: Aug 9, 2025

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Quantum local-equilibrium approach to dissipative hydrodynamics
Joël Mabillard1, Pierre Gaspard1
1Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles, Code Postal 231, Campus Plaine, B-1050 Brussels, Belgium.
This study derives macroscopic hydrodynamic equations for many-body quantum systems using a local-equilibrium approach. It demonstrates non-negative entropy production, aligning with thermodynamic laws for fluids and condensed matter.
Area of Science:
- Quantum mechanics
- Statistical mechanics
- Hydrodynamics
Background:
- Macroscopic hydrodynamic equations are crucial for describing fluid behavior.
- The local-equilibrium approach offers a framework for bridging microscopic and macroscopic descriptions.
- Quantum mechanics provides the fundamental basis for understanding many-body systems.
Purpose of the Study:
- To derive macroscopic hydrodynamic equations for many-body systems within the Schrödinger picture.
- To identify reversible and dissipative parts of current densities and their time evolution.
- To establish a connection between quantum mechanics and thermodynamic principles.
Main Methods:
- Utilizing the local-equilibrium approach and the Schrödinger picture.
- Defining statistical operators based on microscopic densities and macrofields.
- Applying functional identities and projection-operator methods.
- Employing the Peierls-Bogoliubov inequality and quantum integral fluctuation theorem.
Main Results:
- General equations for the time evolution of conjugate macrofields were obtained.
- The entropy production was proven to be nonnegative.
- Transport coefficients were expressed via Green-Kubo formulas.
- Entropy production rate was linked to quantum Einstein-Helfand formulas.
Conclusions:
- The derived hydrodynamic equations are consistent with the second law of thermodynamics.
- The framework is applicable to multicomponent fluids and condensed matter with broken symmetries.
- This work provides a quantum mechanical foundation for macroscopic transport phenomena.
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