Quantum bath effects on nonequilibrium heat transport in model molecular junctions

Area of Science:

• Computational Physics
• Quantum Dynamics
• Thermodynamics

Background:

• Quantum-classical dynamics simulations are vital for studying nonequilibrium heat transport in molecular systems.
• Current simulations often use classical distributions for initial bath conditions, potentially introducing inaccuracies.

Purpose of the Study:

• To investigate the impact of quantum versus classical initial bath sampling on steady-state heat currents.
• To analyze these effects in the nonequilibrium spin-boson model, a key system for single-molecule junctions.

Main Methods:

• Performing quantum-classical dynamics simulations.
• Comparing heat transport results using initial bath conditions sampled from quantum and classical distributions.
• Analyzing the spin-boson model across various parameter regimes.

Main Results:

• Classical bath sampling yielded 1.3-4.5 times larger steady-state heat currents than quantum sampling across many parameters.
• Turnovers in heat current were observed with both sampling methods, but were sharper and showed different temperature dependencies with classical sampling.
• Differences in heat currents increased with temperature gaps and decreased, but remained non-negligible, at higher bath temperatures.

Conclusions:

• Quantum bath sampling is essential for accurate quantum-classical dynamics simulations of heat transport.
• The choice of bath sampling significantly influences simulation outcomes, particularly in nonequilibrium scenarios.
• The steady-state fluctuation theorem was only observed under Markovian conditions with quantum bath sampling.