198 research outputs found

    Quantum and classical correlations in the one-dimensional XY model with Dzyaloshinskii-Moriya interaction

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    We study the effect of Dzyaloshinskii-Moriya (DM) interaction on pairwise quantum discord, entanglement, and classical correlation in the anisotropic XY spin-half chain. Analytical expressions for both quantum and classical correlations are obtained from the spin-spin correlation functions. We show that these pairwise quantities exhibit various behaviors in relation to the relative strengths of the DM interaction, the anisotropy and the magnetic intensity. We observe non-analyticities of the derivatives of both quantum and classical correlations with respect to the magnetic intensity at the critical point, with consideration of the DM interaction.Comment: 18pages, 6figure

    Revisiting the quantum Szilard engine with fully quantum considerations

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    By considering level shifting during the insertion process we revisit the quantum Szilard engine (QSZE) with fully quantum consideration. We derive the general expressions of the heat absorbed from thermal bath and the total work done to the environment by the system in a cycle with two different cyclic strategies. We find that only the quantum information contributes to the absorbed heat, and the classical information acts like a feedback controller and has no direct effect on the absorbed heat. This is the first demonstration of the different effects of quantum information and classical information for extracting heat from the bath in the QSZE. Moreover, when the well width L→∞L\rightarrow \infty or the temperature of the bath T→∞T\rightarrow \infty the QSZE reduces to the classical Szilard engine (CSZE), and the total work satisfies the relation Wtot=kBTln2W_{\mathtt{tot}}=k_{B}T \mathtt{ln}2 as obtained by Sang Wook Kim et al. [Phys. Rev. Lett. 106, 070401 (2011)] for one particle case.Comment: 17 pages, 3 figures, to be published in Annals of Physics(NY

    Spectral self-adaptive absorber/emitter for harvesting energy from the sun and outer space

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    The sun (~6000 K) and outer space (~3 K) are the original heat source and sink for human beings on Earth. The energy applications of absorbing solar irradiation and harvesting the coldness of outer space for energy utilization have attracted considerable interest from researchers. However, combining these two functions in a static device for continuous energy harvesting is unachievable due to the intrinsic infrared spectral conflict. In this study, we developed spectral self-adaptive absorber/emitter (SSA/E) for daytime photothermal and nighttime radiative sky cooling modes depending on the phase transition of the vanadium dioxide coated layer. A 24-hour day-night test showed that the fabricated SSA/E has continuous energy harvesting ability and improved overall energy utilization performance, thus showing remarkable potential in future energy applications.Comment: 15 pages, 4 figure

    An analytical study of the nocturnal radiative cooling potential of typical photovoltaic/thermal module

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    Radiative cooling (RC) sees great developments in recent years due to its unique feature of sending waste heat to the cold universe without any additional energy consumption, which is extensively proved in many application scenarios, including its integration into solar installations. The comprehensive solar photovoltaic/thermal (PV/T) technology is becoming popular due to its multi-function and high overall efficiency. The integration of RC into a PV/T collector can further contribute to such merits by adding a night sky cooling function, so a PV/T-RC collector can produce electricity and heat during the daytime and provide cooling energy during the nighttime. Without any structural modification, a flat-plate PV/T collector with a typical glass cover is confirmed to be able to realize a good radiative cooling in the present study. A mathematic model for the nighttime performance evaluation of a typical PV/T module was developed to characterize the nocturnal cooling capacity of the module. Results suggest that the absorber plate can be cooled to nearly 9.5 °C below the ambient air over a consecutive five hours nighttime period. Further parametric studies were carried out to investigate the effect of some key structural and environmental parameters on the radiative cooling performance of the PV/T module. Under some favorable radiative cooling conditions, the absorber plate can realize a stagnation temperature of nearly 11 °C lower than the ambient temperature and reach a maximum cooling power of over 50 W/m2
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