Structure and stability of quasi-two-dimensional boson-fermion mixtures with vortex-antivortex superposed states

We investigate the equilibrium properties of a quasi-two-dimensional degenerate boson-fermion mixture (DBFM) with a bosonic vortex-antivortex superposed state (VAVSS) using a quantum-hydrodynamic model. We show that, depending on the choice of parameters, the DBFM with a VAVSS can exhibit rich phase structures. For repulsive boson-fermion (BF) interaction, the Bose-Einstein condensate (BEC) may constitute a petal-shaped "core" inside the honeycomb-like fermionic component, or a ring-shaped joint "shell" around the onion-like fermionic cloud, or multiple segregated "islands" embedded in the disc-shaped Fermi gas. For attractive BF interaction just below the threshold for collapse, an almost complete mixing between the bosonic and fermionic components is formed, where the fermionic component tends to mimic a bosonic VAVSS. The influence of an anharmonic trap on the density distributions of the DBFM with a bosonic VAVSS is discussed. In addition, a stability region for different cases of DBFM (without vortex, with a bosonic vortex, and with a bosonic VAVSS) with specific parameters is given.Comment: 8 pages,5 figure

Anomalous tunneling conductances of a spin singlet \nu=2/3 edge states: Interplay of Zeeman splitting and Long Range Coulomb Interaction

The point contact tunneling conductance between edges of the spin singlet $\nu=2/3,\hat{K}=(3/3/0)$ quantum Hall states is studied both in the quasiparticle tunneling picture and in the electron tunneling picture. Due to the interplay of Zeeman splitting and the long range Coulomb interaction between edges of opposite chirality novel spin excitations emerge, and their effect is characterized by anomalous exponents of the charge and spin tunneling conductances in various temperature ranges. Depending on the kinds of scatterings at the point contact and the tunneling mechanism the anomalous interaction in spin sector may enhance or suppress the tunneling conductances. The effects of novel spin excitation are also relevant to the recent NMR experiments on quantum Hall edges.Comment: Revtex File, 7 pages: To be published in Physical Reviews

A HREM study of the atomic structure and the growth mechanism of the YBa2Cu3O7/YSZ interface

The interface between yttria-stabilized zirconia (YSZ) substrate and YBa2Cu3O7 (YBCO) film was studied by high-resolution electron microscopy. In all specimens we have observed an intermediate layer of BaZrO3 located between the substrate YSZ and YBCO. The BaZrO3 layer is composed of almost equally aligned domains being 4¿8 nm in the lateral directions. Reaction products such as Y and Cu oxides were never observed in or close to the BaZrO3 reaction layer but they do occur in the YBCO film. The stacking sequence of BaZrO3/YBCO is predominantly (BaZrO3)-ZrO2-BaO/CuO-BaO-(YBCO) with CuO layer as the beginning YBCO layer. Sometimes a stacking sequence (BaZrO3)-ZrO2-BaO/BaO-CuO2-(YBCO) with a BaO layer as the beginning YBCO layer was observed. This stacking is related to a dislocation with Burgers vector a'/2 [111], where a' = 0.42 nm is the lattice constant of the cubic BaZrO3. Three main epitaxial relations (0°, 45°, 9°) between YSZ and YBCO were observed. These can be explained by near-coincidence site lattices ¿ = 25, ¿ = 49 and ¿ = 13 (for a YSZ substrate). Usually the (001) plane of the YBCO film is parallel to the (001) plane of the BaZrO3 layer and parallel to the substrate surface. In case YBCO is grown on an inclined YSZ substrate, the (001) plane of the YBCO film is parallel to the substrate surface and thus not parallel to the (001) plane of the YSZ substrate

Low-Complexity Precoding Design for Massive Multiuser MIMO Systems Using Approximate Message Passing

A practical challenge in the precoding design of massive multiuser multiple-input multiple-output (MIMO) systems is to facilitate hardware-friendly implementation. To achieve this, we propose a low peak-to-average power ratio (PAPR) precoding based on an approximate message passing (AMP) algorithm to minimize multiuser interference (MUI) in massive multiuser MIMO systems. The proposed approach exhibits fast convergence and low complexity characteristics. Compared with a conventional constant-envelope precoding and an annulus-constrained precoding, simulation results demonstrate that the proposed AMP precoding is superior both in terms of computational complexity and average running time. In addition, the proposed AMP precoding exhibits a much desirable tradeoff between MUI suppression and PAPR reduction. These findings indicate that the proposed AMP precoding is a suitable candidate for hardware implementation, which is very appealing for massive MIMO systems

A Research and Strategy of Remote Sensing Image Denoising Algorithms

Most raw data download from satellites are useless, resulting in transmission waste, one solution is to process data directly on satellites, then only transmit the processed results to the ground. Image processing is the main data processing on satellites, in this paper, we focus on image denoising which is the basic image processing. There are many high-performance denoising approaches at present, however, most of them rely on advanced computing resources or rich images on the ground. Considering the limited computing resources of satellites and the characteristics of remote sensing images, we do some research on these high-performance ground image denoising approaches and compare them in simulation experiments to analyze whether they are suitable for satellites. According to the analysis results, we propose two feasible image denoising strategies for satellites based on satellite TianZhi-1.Comment: 9 pages, 4 figures, ICNC-FSKD 201

Landau-Zener Interference in Multilevel Superconducting Flux Qubits Driven by Large Amplitude Fields

We proposed an analytical model to analyze the Landau-Zener interference in a multilevel superconducting flux qubit driven by large amplitude external fields. Our analytical results agree remarkably with those of the experiment [Nature 455, 51 (2008)]. Moreover, we studied the effect of driving-frequency and dephasing rate on the interference. The dephasing generally destroys the interference while increasing frequency rebuilds the interference at large dephasing rate. At certain driving frequency and dephasing rate, the interference shows some anomalous features as observed in recent experiments.Comment: 7 pages, 6 figure

Scaling Analysis and Application: Phase Diagram of Magnetic Nanorings and Elliptical Nanoparticles

The magnetic properties of single-domain nanoparticles with different geometric shapes, crystalline anisotropies and lattice structures are investigated. A recently proposed scaling approach is shown to be universal and in agreement with dimensional analysis coupled with an assumption of {\em incomplete} self-similarity. It is used to obtain phase diagrams of magnetic nanoparticles featuring three competing configurations: in-plane and out-of-plane ferromagnetism and vortex formation. The influence of the vortex core on the scaling behavior and phase diagram is analyzed. Three-dimensional phase diagrams are obtained for cylindrical nanorings, depending on their height, outer and inner radius. The triple points in these phase diagrams are shown to be in linear relationship with the inner radius of the ring. Elliptically shaped magnetic nanoparticles are also studied. A new parametrization for double vortex configurations is proposed, and regions in the phase diagram are identified where the double vortex is a stable ground state.Comment: 9 pages, 7 figures; added references, and discussion, as suggested by referee

Anomalous Exponent of the Spin Correlation Function of a Quantum Hall Edge

The charge and spin correlation functions of partially spin-polarized edge electrons of a quantum Hall bar are studied using effective Hamiltonian and bosonization techniques. In the presence of the Coulomb interaction between the edges with opposite chirality we find a different crossover behavior in spin and charge correlation functions. The crossover of the spin correlation function in the Coulomb dominated regime is characterized by an anomalous exponent, which originates from the finite value of the effective interaction for the spin degree of freedom in the long wavelength limit. The anomalous exponent may be determined by measuring nuclear spin relaxation rates in a narrow quantum Hall bar or in a quantum wire in strong magnetic fields.Comment: 4 pages, Revtex file, no figures. To appear in Physical Revews B, Rapid communication

Resonant Tunneling Between Quantum Hall Edge States

Resonant tunneling between fractional quantum Hall edge states is studied in the Luttinger liquid picture. For the Laughlin parent states, the resonance line shape is a universal function whose width scales to zero at zero temperature. Extensive quantum Monte Carlo simulations are presented for $\nu = 1/3$ which confirm this picture and provide a parameter-free prediction for the line shape.Comment: 14 pages , revtex , IUCM93-00