Double quantum dot coupled to a quantum point contact: A stochastic thermodynamics approach

We study the nonequilibrium properties of an electronic circuit composed of a double quantum dot (DQD) channel coupled to a quantum point contact (QPC) within the framework of stochastic thermodynamics. We show that the transition rates describing the dynamics satisfy a nontrivial local detailed balance (LDB) and that the statistics of energy and particle currents across both channels obeys a fluctuation theorem (FT). We analyze two regimes where the device operates as a thermodynamic machine and study its output power and efficiency fluctuations. We show that the electrons tunneling through the QPC without interacting with the DQD have a strong effect on the device efficiency

Stochastic thermodynamics of rapidly driven systems

We present the stochastic thermodynamics analysis of an open quantum system weakly coupled to multiple reservoirs and driven by a rapidly oscillating external field. The analysis is built on a modified stochastic master equation in the Floquet basis. Transition rates are shown to satisfy the local detailed balance involving the entropy flowing out of the reservoirs. The first and second law of thermodynamics are also identified at the trajectory level. Mechanical work is identified by means of initial and final projections on energy eigenstates of the system. We explicitly show that this two step measurement becomes unnecessary in the long time limit. A steady-state fluctuation theorem for the currents and rate of mechanical work is also established. This relation does not require the introduction of a time reversed external driving which is usually needed when considering systems subjected to time asymmetric external fields. This is understood as a consequence of the secular approximation applied in consistency with the large time scale separation between the fast driving oscillations and the slower relaxation dynamics induced by the environment. Our results are finally illustrated on a model describing a thermodynamic engine.Comment: Equation (31) removed and subsequent discussion improved. References improved and minor corrections. v3: published versio

Predicción de cambios en el fitobentos de las islas Canarias como consecuencia del calentamiento global.

Las macroalgas marinas son los principales productores primarios de los océanos y mares constituyendo la base de muchos ecosistemas que dependen de ellas para sobrevivir. Ante el actual escenario de cambio climático global, se ha observado su regresión y hasta su desaparición en numerosas localidades del litoral mundial, debido al aumento de la temperatura del agua de mar. La distribución biogeográfica de estos organismos está sufriendo notables cambios y según las predicciones de futuros escenarios de calentamiento global, continuará bajo la influencia de las alteraciones de las condiciones ambientales. Con el objetivo de predecir futuras variaciones causadas por el aumento de las temperaturas, se examinaron las áreas de distribución junto con el rango de temperaturas óptimas para el crecimiento de las macroalgas más abundantes del fitobentos marino de las islas Canarias. Se concluye que la temperatura es el principal factor ambiental que determina la distribución geográfica de las macroalgas marinas lo que muestra su alta vulnerabilidad ante el cambio climático, estando más expuesto el límite sur de su distribución. Sin embargo, la mayoría de las especies estudiadas potencialmente tolerarán al menos el incremento de temperatura previsto en las islas Canarias para el 2100.Marine macroalgae are the primary producers of the oceans and seas which are the basis of many ecosystems that depend on them for survival. Given the current scenario of global climate change, its regression and even disappearance has been observed in many locations along the world’s coastline, due to the rise in sea water temperature. The biogeographical distribution of these organisms is undergoing significant changes and according to predictions of future global warming scenarios, it will continue to be influenced by the alterations of environmental conditions. In order to predict future variations caused by the increasing temperatures, the areas of distribution along with the range of optimal temperatures for the growth of the most abundant macroalgae of the marine phytobenthos of the Canary islands were examined. We conclude that temperature is the main environmental factor that determines the geographical distribution of marine macroalgae, which shows their high vulnerability to climate change, with the southern limit of their distribution being more exposed. However, most of the species studied will potentially tolerate at least the increase in temperature predicted in the Canary islands for 2100

Conservation laws and symmetries in stochastic thermodynamics

Phenomenological nonequilibrium thermodynamics describes how fluxes of conserved quantities, such as matter, energy, and charge, flow from outer reservoirs across a system and how they irreversibly degrade from one form to another. Stochastic thermodynamics is formulated in terms of probability fluxes circulating in the system’s configuration space. The consistency of the two frameworks is granted by the condition of local detailed balance, which specifies the amount of physical quantities exchanged with the reservoirs during single transitions between configurations. We demonstrate that the topology of the configuration space crucially determines the number of independent thermodynamic affinities (forces) that the reservoirs generate across the system and provides a general algorithm that produces the fundamental affinities and their conjugate currents contributing to the total dissipation, based on the interplay between macroscopic conservations laws for the currents and microscopic symmetries of the affinities

3D model for indoor spaces using depth sensor

In recent years, 3D model for indoor spaces have become highly demanded in the development of technology. Many approaches to 3D visualisation and modelling especially for indoor environment was developed such as laser scanner, photogrammetry, computer vision, image and many more. However, most of the technique relies on the experience of the operator to get the best result. Besides that, the equipment is quite expensive and time-consuming in terms of processing. This paper focuses on the data acquisition and visualisation of a 3D model for an indoor space by using a depth sensor. In this study, EyesMap3D Pro by Ecapture is used to collect 3D data of the indoor spaces. The EyesMap3D Pro depth sensor is able to generate 3D point clouds in high speed and high mobility due to the portability and light weight of the device. However, more attention must be paid on data acquisition, data processing, visualizing, and evaluation of the depth sensor data. Hence, this paper will discuss the data processing from extracting features from 3D point clouds to 3D indoor models. Afterwards, the evaluation on the 3D models is made to ensure the suitability in indoor model and indoor mapping application. In this study, the 3D model was exported to 3D GIS-ready format for displaying and storing more information of the indoor spaces

Time-reversal symmetry relations for currents in quantum and stochastic nonequilibrium systems

An overview is given of recent advances in the nonequilibrium statistical mechanics of quantum systems and, especially, of time-reversal symmetry relations that have been discovered in this context. The systems considered are driven out of equilibrium by time-dependent forces or by coupling to large reservoirs of particles and energy. The symmetry relations are established for the exchange of energy and particles between the subsystem and its environment. These results have important consequences. In particular, generalizations of the Kubo formula and the Casimir-Onsager reciprocity relations can be deduced beyond linear response properties. Applications to electron quantum transport in mesoscopic semiconducting circuits are discussed.Comment: Chapter contributed to: R. Klages, W. Just, and C. Jarzynski (Eds.), Nonequilibrium Statistical Physics of Small Systems: Fluctuation Relations and Beyond (Wiley-VCH, Weinheim, 2012; ISBN 978-3-527-41094-1

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