Spontaneous symmetry breaking at the fluctuating level.

Area of Science:

• Statistical physics
• Non-equilibrium systems
• Complex systems

Background:

• Equilibrium thermodynamics typically forbids phase transitions in steady states.
• Fluctuations can drive systems out of equilibrium, leading to novel phenomena.
• Understanding non-equilibrium dynamics is crucial for many scientific fields.

Purpose of the Study:

• To experimentally observe and characterize phase transitions at the fluctuating level in an isolated diffusive system.
• To investigate the statistical properties of current fluctuations above a critical threshold.
• To explore the relationship between rare events and self-organized patterns.

Main Methods:

• Measurement of current fluctuations in an isolated diffusive system.
• Analysis of fluctuation statistics, comparing small fluctuations to those above a critical current.
• Comparison of experimental results with predictions from hydrodynamic fluctuation theory.

Main Results:

• Observed a novel phenomenon where phase transitions occur at the fluctuating level, not in equilibrium steady states.
• Demonstrated that small current fluctuations arise from local events, while large fluctuations involve self-organization into a traveling wave.
• Identified a transition from Gaussian statistics for small fluctuations to non-Gaussian tails for currents above a critical threshold.
• Experimental results align with theoretical predictions from hydrodynamic fluctuation theory.

Conclusions:

• Rare events in non-equilibrium systems are often associated with coherent, self-organized patterns.
• These patterns facilitate and enhance the probability of large current deviations.
• The findings challenge traditional views of phase transitions and highlight the importance of fluctuations in driving system behavior.