Quantum Correlations Enable Atomic-Scale Engines to Exceed Carnot Efficiency Limits

Quantum correlations could rewrite thermodynamics' efficiency limits at atomic scales. A peer-reviewed study in Science Advances (DOI: 10.1126/sciadv.adw8462) demonstrates that quantum correlations—non-classical statistical relationships between particles—allow atomic-scale engines to convert both heat and these correlations into work.

This challenges the 200-year-old Carnot principle, which sets a theoretical maximum efficiency for classical heat engines based solely on temperature differences.

The Carnot efficiency limit, formulated in 1824, assumes systems operate in thermal equilibrium and ignores quantum effects. At atomic scales, however, quantum correlations enable work extraction beyond heat alone.

Professor Eric Lutz, a co-author of the study, states, 'Tiny motors, no larger than a single atom, could become a reality in the future.' The research mathematically proves that quantum-correlated systems can achieve higher maximum efficiency than classical engines, though practical implementation remains untested.

Quantum correlations differ from classical correlations in their ability to persist even when particles are spatially separated.

The study clarifies that these correlations are not speculative but measurable phenomena, such as entanglement or discord, which have been experimentally verified in quantum systems.

The authors emphasize that their findings rely on precise mathematical modeling rather than unproven technological assumptions.

Potential applications include nanoscale quantum motors for medical nanobots or material manipulation. However, the team notes that 'it is now also evident that these engines can achieve a higher maximum efficiency than larger heat engines' only under idealized conditions.

Challenges remain in maintaining quantum coherence and scaling up such systems for real-world use.