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Active dynamics of colloidal particles in time-varying laser speckle patterns
Silvio Bianchi1, Riccardo Pruner1, Gaszton Vizsnyiczai1
1Dipartimento di Fisica, Università di Roma "Sapienza", Rome, I-00185, Italy.
Scientific Reports
|June 10, 2016
Summary
Colloidal particles in dynamic light patterns exhibit complex motion. Controlling light speckle correlations tunes particle diffusion, bridging non-equilibrium physics and optical manipulation.
Area of Science:
- Soft Matter Physics
- Non-Equilibrium Statistical Mechanics
- Optical Physics
Background:
- Colloidal particles in dynamic speckle patterns experience fluctuating optical forces.
- This system offers analogies to active colloids and intracellular transport.
- Understanding particle dynamics in random energy landscapes is crucial.
Purpose of the Study:
- To investigate colloidal particle dynamics in controllable, fluctuating light fields.
- To explore the influence of speckle correlation time on particle motion.
- To develop models explaining the observed mean square displacement behavior.
Main Methods:
- Utilizing a spatial light modulator to generate dynamic speckle patterns.
- Creating ring-shaped random patterns to confine colloidal particles.
- Analyzing particle trajectories and calculating mean square displacement.
Main Results:
- Observed diffusive mean square displacement at short and long times.
- Identified superdiffusive or subdiffusive behavior at intermediate times, dependent on speckle correlation time.
- Developed models for short and long correlation time limits.
Conclusions:
- Controllable dynamic speckle patterns provide a versatile platform for studying non-equilibrium systems.
- Speckle correlation time is a key parameter governing colloidal particle diffusion.
- A unified interpolation formula accurately describes the observed dynamics across varying correlation times.
