Thermoelectric information engine driven by an autonomous Maxwell demon across quantum-to-classical transitions
Phys. Rev. E 114, 044121 – Published 13 October, 2026
DOI: https://doi.org/10.1103/3gmr-jnwn
Abstract
We study a three-terminal thermoelectric engine, focusing on the role of quantum coherence and information flow. A double dot connects two reservoirs at different chemical potentials, while a third dot monitors their occupation via Coulomb interaction and can be interpreted as an autonomous Maxwell demon. Within the parameter range where the device operates as an engine, we identify conditions under which this interpretation holds, namely, when a finite information flow toward the monitoring dot is accompanied by negligible energy flow. The system dynamics is described within a Redfield master equation that allows us to identify two distinct dynamical regimes with steady states well captured by suitable Lindblad approximations. For large interdot tunneling, energy-basis coherences vanish, and the steady state reduces to that of a classical stochastic master equation associated with a fully secular approximation. In contrast, for small tunneling, coherence persists in both energy and local eigenbases, and a Lindblad description derived from a partial secular approximation to the Redfield equation must be employed. These two regimes define a first quantum-to-classical transition controlled by the interdot tunneling strength. We further consider the effect of a phonon bath coupled to the double dot, which induces a second quantum-to-classical transition by generating incoherent transport and decoherence in the small interdot tunneling regime. We find a competition between these effects: incoherent transport enhances both particle and information flows, whereas decoherence suppresses them, and this competition governs the effectiveness of the demon. In particular, we identify a parameter region where phonon-induced decoherence suppresses both the coherent transport contribution and the information flow toward the monitoring dot, suggesting that coherence can enhance the demon mechanism in this regime. By tracking information and transport properties across these crossovers, our model shows how coherent tunneling, decoherence, and incoherent phonon-assisted transport compete in an autonomous information engine while clarifying which thermodynamic Lindblad description is appropriate in each regime.
