Quantum Transport of Bosonic Cold Atoms in Double Well Optical Lattices

We numerically investigate, using the time evolving block decimation algorithm, the quantum transport of ultra-cold bosonic atoms in a double well optical lattice through slow and periodic modulation of the lattice parameters (intra- and inter-well tunneling, chemical potential, etc.). The transport of atoms does not depend on the rate of change of the parameters (as along as the change is slow) and can distribute atoms in optical lattices at the quantized level without involving external forces. The transport of atoms depends on the atom filling in each double well and the interaction between atoms. In the strongly interacting region, the bosonic atoms share the same transport properties as non-interacting fermions with quantized transport at the half filling and no atom transport at the integer filling. In the weakly interacting region, the number of the transported atoms is proportional to the atom filling. We show the signature of the quantum transport from the momentum distribution of atoms that can measured in the time of flight image. A semiclassical transport model is developed to explain the numerically observed transport of bosonic atoms in the non-interacting and strongly interacting limits. The scheme may serve as an quantized battery for atomtronics applications.Comment: 8 pages, 9 figures, accepted for publication in Phys. Rev.

SCMA with Low Complexity Symmetric Codebook Design for Visible Light Communication

Sparse code multiple access (SCMA) is attracting significant research interests currently, which is considered as a promising multiple access technique for 5G systems. It serves as a good candidate for the future communication network with massive nodes due to its capability of handling user overloading. Introducing SCMA to visible light communication (VLC) can provide another opportunity on design of transmission protocols for the communication network with massive nodes due to the limited communication range of VLC, which reduces the interference intensity. However, when applying SCMA in VLC systems, we need to modify the SCMA codebook to accommodate the real and positive signal requirement for VLC.We apply multidimensional constellation design methods to SCMA codebook. To reduce the design complexity, we also propose a symmetric codebook design. For all the proposed design approaches, the minimum Euclidean distance aims to be maximized. Our symmetric codebook design can reduce design and detection complexity simultaneously. Simulation results show that our design implies fast convergence with respect to the number of iterations, and outperforms the design that simply modifies the existing approaches to VLC signal requirements

Applicability of the Friedberg-Lee-Zhao method

Friedberg, Lee and Zhao proposed a method for effectively evaluating the eigenenergies and eigen wavefunctions of quantum systems. In this work, we study several special cases to investigate applicability of the method. Concretely, we calculate the ground-state eigenenergy of the Hellmann potential as well as the Cornell potential, and also evaluate the energies of the systems where linear term is added to the Coulomb and harmonic oscillator potentials as a perturbation. The results obtained in this method have a surprising agreement with the traditional method or the numerical results. Since the results in this method have obvious analyticity compared to that in other methods, and because of the simplicity for calculations this method can be applied to solving the Schr\"{o}dinger equation and provides us better understanding of the physical essence of the concerned systems. But meanwhile applications of the FLZ method are restricted at present, especially for certain potential forms, but due to its obvious advantages, it should be further developed.Comment: 14 pages,no figure

A Small Satellite Mission for Solar Coronagraphy

We present on a concept study of the Goddard Miniature Coronagraph (GMC) mission for measuring the plasma flow in the solar corona in the form of solar wind and coronal mass ejections (CMEs). These mass flows can dramatically alter the near-Earth space environment to hazardous conditions posing danger to human technology in space. The primary science objective of the mission is to measure the properties of CMEs, coronal structures, and the solar wind near the Sun. The miniaturization of the coronagraph involves using a single-stage optics and a polarization camera, both of which reduce the size of the coronagraph. GMC will be accommodated in a small satellite that can be built with CubeSat material to minimize cost. The development of the Dellingr mission at NASA/GSFC has provided expertise and a clear pathway to build the GMC mission. The hardware and software used for the Dellingr (a name derived from the god of the dawn in Norse mythology) Mission are technically sound, so the GMC mission can be fully defined. Software, pointing, control and communications systems developed for GSFC CubeSats can be readily adapted to cut costs. We present orbit options such as an ISS (International Space Station) orbit or a Sun-synchronous dawn-dusk polar orbit with the aim of maximizing solar observations

El efecto de los nnuevos medios digitales del "Diario del Pueblo" para la cobertura informativa de la COVID-19

En este trabajo nos adentramos en el efecto de los nuevos medios digitales del Diario del Pueblo, uno de los diez periódicos más conocidos del mundo, ante la COVID-19. Los nuevos medios, gracias a las ventajas distintivas, desempeñan un papel insustituible en la cobertura informativa de la emergencia sanitaria pública. Frente a esta crisis, los tres nuevos medios (Microblog, Wechat, Douyin ) del Diario del Pueblo realizaron las funciones de los medios de comunicación a través de los informes diferenciados según las características de plataformas y las preferencias de audiencias. El artículo busca presentar y analizar cómo integrar orgánicamente los nuevos medios digitales del Diario del Pueblo para el efecto de transmisión óptima en la sociedad china ante la pandemia de la COVID-19 con base en la recopilación de datos y el análisis de estadísticas

Masters of the Nation

Cinema, an extremely popular and useful cultural form during the Maoist era, played a big role in shaping working class subjectivity. This article argues that despite their highly politicised and formalised content, industrial-themed films made during the Cultural Revolution created a “masters of the nation” subjectivity that still resonates with workers who grew up watching these films. In doing so, this article brings together two bodies of scholarship that rarely make reference to one another: filmmaking in the Cultural Revolution period and post-Mao workers’ subjectivity. Post-Mao scholarship has gone beyond simply dismissing films from the Cultural Revolution period as crude propaganda designed to create a highly politicised mass mind. It has drawn our attention to the more complicated nature of this body of filmmaking, particularly the “model play” films. However, new features made during the Cultural Revolution are often seen as “too ideological” to warrant academic attention. This paper attempts to find out how the “masters of the nation” discourse still resonates with workers who grew up watching these films. It argues that, despite the valorisation of workers as the privileged class and an excessive focus on class struggle, these films have indeed endowed the subaltern with the kind of agency that is lacking in contemporary media representations of workers

Les « maîtres de la nation »

Le cinéma, forme culturelle extrêmement populaire et utile pendant l’ère maoïste, a joué un rôle très important dans l’élaboration de la conscience de la classe ouvrière. Les longs métrages réalisés pendant la Révolution culturelle, malgré leur aspect très formel et hautement politisé, ont contribué à inculquer aux ouvriers qui les ont visionnés une représentation d’eux-mêmes comme « maîtres de la nation », représentation à laquelle ils s’identifient encore aujourd’hui. Pour étayer cette thèse, cet article s’appuie sur deux ensembles de travaux académiques faisant rarement référence l’un à l’autre : le premier s’intéresse à la production de films pendant la Révolution culturelle tandis que le second traite des évolutions de la conscience de classe des ouvriers dans l’ère post-maoïste. Les travaux récents ne réduisent plus les films produits pendant la Révolution culturelle à de simples films de propagande conçus pour créer une mentalité de masse hautement politisée. Ces études ont attiré notre attention sur la nature complexe de ce corpus d’oeuvres, particulièrement celles reprenant les « opéras modèles ». Cependant, les films produits pendant la Révolution culturelle sont encore souvent perçus comme « trop idéologiques » pour retenir l’attention des chercheurs. Malgré cette désaffection, cet article analyse la manière dont le discours des « maîtres de la nation » développé par ces oeuvres fait encore écho dans la conscience des travailleurs qui ont grandi en les visionnant. Malgré l’attention excessive qu’elles accordent à la lutte des classes et la survalorisation des ouvriers qui y sont représentés comme une classe privilégiée, cet article souhaite montrer que ces œuvres cinématographiques ont contribué à créer chez les classes subalternes une représentation d’elles-mêmes et des dispositions faisant défaut dans la représentation médiatique contemporaine des ouvriers