Coherent and exotic heat machines

In the first part of the talk, our recent experimental observation of quantum effects in the operation of microscopic heat machines in NV centers in diamonds will be presented. Interestingly, we find that it is preferable to have weaker thermalization strokes in order to preserve quantum coherence and boost the work extraction strokes of the engine. Moreover,  the experiment confirms the prediction that when the ‘engine action’ is small compared to h-bar, different types of machines (two-stroke, four-stroke, etc.) become thermodynamically equivalent to each other. This result also holds far from steady state operation. The second part of the talk, deals with 'exotic heat machines’: machines that use thermodynamic resources (work & heat) to carry out a non-thermodynamics task. Since the output of these machines involves observables which do not appear in the second law, their performance is not directly limited by the second law of thermodynamics. This motivates the development of 'high-resolution thermodynamics' for isolated quantum setups such as ion traps, cold atoms in optical lattices, Rydberg atoms, and superconducting circuits. Our first steps in this direction will be presented.