Coulomb interaction and quantum transport through a coherent scatterer

Area of Science:

• Quantum transport phenomena
• Condensed matter physics
• Mesoscopic physics

Background:

• Quantum transport is influenced by fundamental interactions like charge discreteness, coherent scattering, and Coulomb interactions.
• Understanding these interplay effects is crucial for advancing quantum devices and nanoscale electronics.

Purpose of the Study:

• To investigate the combined effects of charge discreteness, coherent scattering, and Coulomb interactions on quantum transport.
• To derive a theoretical framework for analyzing current-voltage characteristics in the presence of these interactions.
• To identify universal behaviors in conductance corrections under specific conditions.

Main Methods:

• Derivation of a real-time effective action for an arbitrary coherent scatterer.
• Development of an equivalent quantum Langevin equation to model the system.
• Evaluation of current-voltage characteristics, focusing on interaction corrections to conductance.

Main Results:

• The interplay of charge discreteness, scattering, and Coulomb interaction leads to nontrivial quantum transport effects.
• A universal factor causing conductance suppression was identified at large conductances and low temperatures (outside the instanton regime).
• This suppression factor is independent of system size and depends only on the conductor's type.

Conclusions:

• The derived effective action and quantum Langevin equation provide a robust model for quantum transport with interactions.
• The observed universal conductance suppression highlights a fundamental aspect of interacting quantum conductors.
• This finding has implications for the design and understanding of quantum devices operating at low temperatures.