Colloidal dynamics over a tilted periodic potential: Nonequilibrium steady-state distributions.

Area of Science:

• Statistical Physics
• Soft Matter Physics
• Colloidal Systems

Background:

• Detailed balance is a fundamental concept in equilibrium statistical mechanics.
• Nonequilibrium steady-state (NESS) systems exhibit persistent particle flux and broken detailed balance.
• Understanding particle dynamics under external forces is crucial for various physical phenomena.

Purpose of the Study:

• To investigate the effects of external force on the NESS dynamics of diffusing particles.
• To explore how breaking detailed balance influences particle distribution.
• To develop analytical methods for characterizing potentials in driven systems.

Main Methods:

• Constructed a tilted two-layer colloidal system with a periodic potential.
• Applied an external force by tilting the sample relative to gravity.
• Measured the NESS probability density function (P(ss)(x,y)).
• Compared experimental results with 1D and 2D Smoluchowski equation solutions.

Main Results:

• NESS probability density function deviates from equilibrium distribution, depending on driving.
• Developed an analytical method to extract 1D potential from P(ss)(x) using the 1D Smoluchowski equation solution.
• Demonstrated deviation from equilibrium is dependent on the driving force.

Conclusions:

• Tilted periodic potentials serve as a platform for studying forced barrier-crossing dynamics.
• The study provides insights into systems beyond the Arrhenius-Kramers equation.
• The developed analytical method accurately extracts potential information from NESS measurements.