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

Riset Tata Kelola Perusahaan dan Efisiensi Investasi

Masalah investasi yang tidak efisien selalu menjadi topik penelitian yang penting, sementara masalah tata kelola perusahaan masih relatif menonjol, dan kualitas informasi akuntansi yang tidak sempurna, sehingga terjadi over-investment dan under-investment, yang semuanya berdampak pada stagnasi. Masalah sosial yang terus muncul juga memperdalam kontradiksi antara pemangku kepentingan terkait. Ditambah dengan ketidakstabilan pasar keuangan internasional, masalah ekonomi dan perdagangan juga berdampak negatif pada perkembangan perusahaan, dan perusahaan harus menghadapi masalah asimetri informasi dan keagenan, yang berdampak pada non-profitabilitas perusahaan. investasi efisiensi. Makalah ini menganalisis secara mendalam masalah investasi yang tidak efisien dari perspektif tata kelola perusahaan dan kualitas informasi akuntansi, serta menggunakan metode kualitatif dan kuantitatif untuk melihat efisiensi investasi perusahaan secara lebih komprehensif. Pengambilan keputusan investasi selalu menjadi salah satu masalah keuangan yang paling diperhatikan bagi perusahaan - semakin efektif investasi, semakin dapat mendorong pertumbuhan ekonomi perusahaan dan meningkatkan daya saing industrinya. Sebaliknya, investasi yang tidak efektif akan menghambat perkembangan perusahaan yang ramah dan melemahkan daya saing pasar mereka.Oleh karena itu, sangat penting bagi perusahaan untuk mempelajari bagaimana mencapai efisiensi investasi perusahaan yang optimal