Stephanie Wehner

Quantum thermodynamics for arbitrarily small devices

QuTech, TU Delft   

The laws of thermodynamics as we know them apply to devices consisting of many particles. Quantum effects and our inability to apply the law of large numbers to systems consisting of a small number of particles, make it challenging to derive laws that apply to even the smallest quantum devices.  Recently, we have proven a second law that applies to even the smallest devices (PNAS 112, 3275 (2015)).

In this talk we will take a look at the maximum efficiency   of heat engines. We will see that at the nano scale, this law needs to be revised in the sense that more information about the bath other than its temperature is required to decide whether maximum efficiency can be achieved. In particular, we derive new fundamental limitations of the efficiency of heat engines at the nano and quantum scale that show that the Carnot efficiency can only be achieved under special circumstances, and we derive a new maximum efficiency for others.