An autonomous out of equilibrium Maxwell's demon for controlling the energy fluxes produced by thermal fluctuations

Characterizing autonomous Maxwell demons

“…which in turn imply T 4 < T 2 , i.e., the demon must have access to a reservoir with a temperature lower than the minimum temperature of the reservoirs in contact with the system. This is also the case in the examples in [18,19], and it can be seen that it is a general feature of linear [20]. Note that the condition J int = 0 implies J 2 = −J 1 , so a local observer that only has access to the values of J 1 and J 2 might jump to the conclusion these two are actually the same flow, which was reversed by the demon.…”

“…Given a partition separating the degrees of freedom of the system from those of the demon, we can also identify an internal energy current J int between them. In this context, the following conditions were proposed in [18,19] to characterize a 'nonequilibrium Maxwell demon': , in such a way that the currents J 1/2 are reversed. However, the current JS through the system remains invariant.…”

“…Both of them are quantum systems, but this is not essential. The example provided in [19] is classical, and consists of a circuit with several noisy resistors, that play the role of the thermal reservoirs. However, as we will see, it is not necessary to consider quantum nor classical fluctuations to achieve the conditions of the previous section (from where it follows that correlations between currents are also not essential).…”

“…Many model systems [8][9][10][11] as well as experiments [12][13][14][15][16][17] have realized such traditional demons. Recent interesting proposals have shown that similar effects can be achieved in linear systems out of equilibrium [18,19]. In these proposals, a new kind of demons is characterized ('nonequilibrium demons' or 'N-demons'), that cannot be interpreted in terms of measurements and feedback control, and in which the only resource is the access to a nonequilibrium distribution.…”

“…To emphasize this distinction, we take these proposals to their most essential form by considering thermal circuits in which on has access to the internal currents, in addition to the reservoir currents. From this it follows that, according to the criteria accepted in [18,19], a demon could be constructed using an extremely simple and deterministic thermal circuit. When stricter traditional criteria are used, then those simple setups are ruled out.…”