Probability Currents in Quantum Thermal Machines

We present core ideas of quantum thermodynamics and a simple model of continuous quantum heat engines, relating their efficiency to the fundamental limit set by the Second Law. We apply a probability current analysis to these systems, allowing us to better understand their steady state behavior. Finally, we introduce a simple quantum mechanical model of Maxwell’s Demon—a system that extracts energy from a thermal reservoir at the cost of writing information to its memory—and analyze its behavior for a range of possible reservoir and memory tape parameters. We find that the information efficiency of our system is bounded by Landauer’s Principle and that it can approach this bound when its thermal reservoir and memory tape are nearly equally mixed.