Minimally nonlinear probe-controlled Aharonov–Bohm heat engines with broken time-reversal symmetry: Surpassing the Curzon–Ahlborn limit

Abstract

We investigate minimally nonlinear three-terminal thermoelectric voltage and voltage- temperature probe heat engines with broken time-reversal symmetry, induced by magnetic flux. By extending Onsager relations with a leading-order nonlinear dissipation term, we obtain analytical bounds for both the efficiency at maximum power (EMP) and the efficiency at arbitrary power. Remarkably, both probe configurations exhibit universal EMP bounds that exceed the Curzon–Ahlborn limit, though with distinct dependence on asymmetry and figures of merit. Using a triple-quantum-dot Aharonov–Bohm interferometer as a model system, we demonstrate how magnetic flux and energy anisotropy tune performance: the voltage probe maximizes power, while the voltage–temperature probe achieves higher efficiency. These results establish minimally nonlinear probe heat engines as a generic pathway to surpassing classical efficiency limits in nanoscale thermodynamics.