Towards quantum thermodynamics in electronic circuits

Electronic circuits operating at sub-kelvin temperatures are attractive candidates for studying classical and quantum thermodynamics: their temperature can be controlled and measured locally with exquisite precision, and they allow experiments with large statistical samples. The availability and rapid development of devices such as quantum dots, single-electron boxes and superconducting qubits only enhance their appeal. But although these systems provide fertile ground for studying heat transport, entropy production and work in the context of quantum mechanics, the field remains in its infancy experimentally. Here, we review some recent experiments on quantum heat transport, fluctuation relations and implementations of Maxwell’s demon, revealing the rich physics yet to be fully probed in these systems.Peer reviewe

A structural approach to cranial variation in the genus 'Alouatta' (Primates, Atelidae)

Howler monkeys (genus 'Alouatta') display a peculiar cranial architecture, characterized by a high degree of airorhynchy. This condition may be evolutionarily influenced by a largely folivory diet (with selective pressures on mandibular and splachnocranial dimensions), social structure (related to the development of vocal sacs), or by the interaction between these or other more subtle factors. In terms of functional craniology, airorhynchy may be related to structural changes associated with the morphology of the supraorbital anatomy, with the spatial relationships between face and cranial base, or with morphogenetic variations of the pteric area. However the evolutionary changes associated with the cranial organization in 'Alouatta' are still currently unknown. This study is aimed at investigating the variation and covariation patterns in howler monkeys, considering both interand intrageneric morphological differences. We also investigated the structural role of the pteric area within the cranial functional matrix, in order to test possible relationships between its variation and the degree of airorhynchy. To address these objectives we applied landmark-based analysis and multivariate statistics to a comparative dataset of atelid adult skulls. Our results suggest that the cranial architecture in howlers is influenced by an allometric vector, which associates higher degrees of airorhynchy with splachnocranial enlargement, basicranial lengthening and neurocranial flattening. On the other hand, the relationship between pterion and airorhynchy could not be confirmed. Either way some minor morphological differences were identified, suggesting that variations of the pteric area may be instead related with the relative development of the masticatory apparatus

Fluctuation theorems for capacitively coupled electronic currents

The counting statistics of electron transport is studied theoretically in a system with two capacitively coupled parallel transport channels. Each channel is composed of a quantum dot connected by tunneling to two reservoirs. The nonequilibrium steady state of the system is controlled by two affinities or thermodynamic forces, each one determined by the two reservoirs of each channel. The status of a single-current fluctuation theorem is investigated starting from the fundamental two-current fluctuation theorem, which is a consequence of microreversibility.We show that the single-current fluctuation theorem holds in the limit of a large Coulomb repulsion between the two parallel quantum dots, as well as in the limit of a large current ratio between the parallel channels. In this latter limit, the symmetry relation of the single-current fluctuation theorem is satisfied with respect to an effective affinity that is much lower than the affinity determined by the reservoirs. This backaction effect is characterized quantitatively