Quantum mechanics trumps the second law of thermodynamics at the atomic scale

Amazing stuff!

"Two physicists at the University of Stuttgart have proven that the Carnot principle, a central law of thermodynamics, does not apply to objects on the atomic scale whose physical properties are linked (so-called correlated objects). This discovery could, for example, advance the development of tiny, energy-efficient quantum motors.  ..."

"... In recent years, quantum mechanical experiments have succeeded in reducing the size of heat engines to the microscopic range. “Tiny motors, no larger than a single atom, could become a reality in the future,” ..."

From the abstract:

"The laws of thermodynamics strongly restrict the performance of thermal machines.

Standard thermodynamics, initially developed for uncorrelated macroscopic systems, does not hold for microscopic systems correlated with their environments.

We here derive an exact formula for the efficiency of any cyclically driven quantum engine by using generalized laws of quantum thermodynamics that account for all possible correlations between all involved parties, including initial correlations.

Furthermore, we demonstrate the existence of two basic modes of engine operation: the usual thermal case, where heat is converted into work, and an athermal regime, where work is extracted from entropic resources, such as system-bath correlations.

In the latter regime, the efficiency is not bounded by the usual Carnot formula. Our results provide a unified formalism to determine the efficiency of correlated microscopic quantum machines."

Quantum mechanics trumps the second law of thermodynamics at the atomic scale

More efficient than Carnot: Quantum mechanics trumps the second law of thermodynamics (original news release) "Two physicists at the University of Stuttgart have proven that the Carnot principle, a central law of thermodynamics, does not apply to objects on the atomic scale whose physical properties are linked (so-called correlated objects). This discovery could, for example, advance the development of tiny, energy-efficient quantum motors."

Correlated quantum machines beyond the standard second law (open access)

Fig. 1. Operation regimes of correlated engines.

Fig. 2. Two-oscillator quantum engine.