Figure 5
SNS system as a thermodynamic machine. (a) Scheme of a cycle in the entropy/temperature plane, consisting in the two iso-entropic processes 1–2 and 3–4 and the two iso-phasic processes 2–3 and 4–1. The red area represents the heat (released or absorbed) in the process 2–3. The light blue area is the work W (done or received) in a complete cycle. The cycle can be used as engine or cooler machine if performed respectively counter-clockwise or clockwise. (b) Work W of the engine as a function of the hot temperature TR at fixed \({T}_{L}={10}^{-3}{T}_{c}\). Different curves refer to some values of a. Dashed curves are analytical solutions obtained within the KO theory. The curves are defined when \({T}_{R}\ge {T}_{{\rm{act}}}\). (c) Thermodynamic efficiency \(\eta \) of the Josephson engine, for different a, as a function of TR/Tc, with \({T}_{L}={10}^{-3}{T}_{c}\). The black dot-dashed curve represents the Carnot limit 1 − TL/TR. The curves are defined for \({T}_{R}\ge {T}_{{\rm{act}}}\).
