Electron transfer statistics and thermal fluctuations in molecular junctions

Area of Science:

• Condensed Matter Physics
• Quantum Transport Phenomena
• Statistical Mechanics

Background:

• Understanding electron transport in quantum systems is crucial for nanoscale electronics.
• Thermal fluctuations significantly influence quantum transport dynamics.
• Previous models often simplified or neglected the role of thermal noise.

Purpose of the Study:

• To derive analytical expressions for the probability distribution function (PDF) of electron transport.
• To investigate the role of thermal fluctuations on electron transfer statistics in a quantum junction.
• To analyze the interplay between thermal fluctuations and shot noise.

Main Methods:

• Utilized large deviation theory combined with the generating function method.
• Derived analytical expressions for the PDF of electron transport.
• Analyzed fluctuation statistics using the Fano factor and delay time distributions.

Main Results:

• The PDF exhibits exponential decay in tails with bias-dependent rates, linked to the fluctuation theorem.
• Thermal fluctuations suppress average current but enhance transfer fluctuations, leading to bunching/antibunching.
• Exact expressions for delay time distribution were obtained; optimal delay times can be reduced by thermal effects.

Conclusions:

• Thermal fluctuations quantitatively alter electron transfer statistics and compete with shot noise.
• Tuning thermal effects offers a pathway to optimize electron transfer delay times below shot noise limits.
• The findings provide fundamental insights into quantum transport under realistic thermal conditions.