Towards Noise Simulation in Interacting Nonequilibrium Systems Strongly Coupled to Baths.

Area of Science:

• Condensed Matter Physics
• Quantum Transport
• Nanoscale Science

Background:

• Advancements in nanoscale experimental techniques enable direct measurement of noise in molecular junctions.
• Noise measurements provide unique information inaccessible through average transport measurements.
• Emerging fields like optoelectronics and quantum thermodynamics highlight the growing importance of transport statistics.

Purpose of the Study:

• To introduce and validate a new theoretical method for evaluating noise characteristics in first-principles simulations.
• To assess the suitability of the nonequilibrium diagrammatic technique for systems with varying interaction strengths.
• To compare the new method's performance against existing approaches and exact solutions.

Main Methods:

• Utilized a recently developed nonequilibrium diagrammatic technique based on Hubbard Green functions.
• Simulated noise and noise spectra in generic models representing non-, weakly, and strongly interacting systems.
• Compared simulation results with exact data and results from established methods tailored to specific interaction regimes.

Main Results:

• The nonequilibrium diagrammatic technique proved effective for calculating noise characteristics across a wide parameter range.
• The method demonstrated viability for systems with weak, moderate, and strong intra-system interactions.
• Simulations showed good agreement with exact data and benchmarked favorably against specialized methods.

Conclusions:

• The proposed diagrammatic technique offers a computationally efficient and versatile approach for first-principles noise calculations.
• This method is suitable for studying quantum transport phenomena in molecular junctions under diverse interaction conditions.
• The findings pave the way for more accurate theoretical predictions of noise in nanoscale electronic devices.