Related Experiment Video
Updated: Aug 28, 2025

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Thermodynamic uncertainty relation for Langevin dynamics by scaling time
Rueih-Sheng Fu1, Todd R Gingrich1
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
This study introduces a unified approach using large deviation theory to establish thermodynamic uncertainty relation (TUR)-like bounds for both overdamped and underdamped Langevin dynamics, offering new insights into fluctuation-dissipation theorems.
Area of Science:
- Statistical Mechanics
- Non-equilibrium Thermodynamics
- Stochastic Processes
Background:
- The thermodynamic uncertainty relation (TUR) connects current fluctuations and dissipation in non-equilibrium systems.
- Existing TUR bounds are well-established for overdamped Langevin dynamics.
- Underdamped Langevin dynamics present complexities due to dynamical activity, requiring different analytical approaches.
Purpose of the Study:
- To develop a unified theoretical framework for TUR-like bounds applicable to both overdamped and underdamped Langevin dynamics.
- To explore an alternative perspective using large deviation theory for analyzing current fluctuations.
- To derive and analyze new TUR-like bounds based on scaled current fluctuations.
Main Methods:
- Application of large deviation theory to analyze current fluctuations in Langevin dynamics.
- Development of a unified approach for both overdamped and underdamped systems.
- Time-scaling techniques applied to current fluctuations.
Main Results:
- A general, unified treatment of TUR-like bounds is established for both overdamped and underdamped Langevin dynamics.
- The derived bounds show similarities to, yet distinct differences from, previously known results.
- The large deviation theory approach provides a novel perspective on these bounds.
Conclusions:
- Large deviation theory offers a powerful and unified tool for investigating thermodynamic uncertainty relations in various dynamical regimes.
- The study provides a new set of TUR-like bounds with potential implications for understanding non-equilibrium statistical mechanics.
- The findings highlight the importance of considering system dynamics and fluctuation scaling in bounding thermodynamic quantities.
Related Concept Videos
Second Law of Thermodynamics
Entropy and the Second Law of Thermodynamics
The relation between entropy and disorder can be illustrated with the example of the phase change of ice to water. In ice, the molecules are located at specific sites giving a solid state, whereas, in a liquid form, these molecules are much freer to move. The molecular arrangement has therefore become more randomized. Although the change in average...
Path Between Thermodynamics States
The Second Law of Thermodynamics
Maxwell's Thermodynamic Relations
All thermodynamic potentials are exact differentials. Therefore, their second-order...
Thermodynamics: Activity Coefficient
The activity coefficient is a measure of the deviation from ideal behavior. When the ionic strength of the solution is minimal, the activity coefficient of an ionic species is close to unity, making...

