Experimental demonstration of quantum effects in the operation of microscopic heat engines

Understand

The heat engine, a machine that extracts useful work from thermal sources, is one of the basic theoretical constructs and fundamental applications of classical thermodynamics.

• The classical description of a heat engine does not include coherence in its microscopic degrees of freedom.
• By contrast, a quantum heat engine might possess coherence between its internal states.
• Although the Carnot efficiency cannot be surpassed, and coherence can be performance degrading in certain conditions, it was recently predicted that even when using only thermal resources, internal coherence can enable a quantum heat engine to produce more power than any classical heat engine using the same resources.