Three-dimensional topological insulators are characterized by the presence of a bandgap in their bulk and gapless Dirac fermions at their surfaces. New physical phenomena originating from the presence of the Dirac fermions are predicted to occur, and to be experimentally accessible via transport measurements in suitably designed electronic devices. Here we study transport through superconductin...

The Gutzwiller wave function for the three-band Hubbard model on a two dimensional CuO2 plane is studied by using the variational Monte Carlo (VMC) method in the limit Ud → ∞, where Ud is the Coulomb repulsion between holes on a Cu site. The VMC results for the energy and the fraction of d-holes are compared with those of the Rice-Ueda type Gutzwiller approximation (GA). The difference between ...

Image completion is an important photo-editing task which involves synthetically filling a hole in the image such that the image still appears natural. State-of-the-art image completion methods work by searching for patches in the image that fit well in the hole region. Our key insight is that image patches remain natural under a variety of transformations (such as scale, rotation and brightnes...

We present a nonperturbative method for deriving a quasiparticle description of the low-energy excitations in the t−J model for strongly correlated electrons. Using the exact diagonalization technique we evaluated exactly the spectral functions of composite operators, which describe an electron or hole dressed by antiferromagnetic spin fluctuations as expected in the string or spin bag picture....

This paper proposes a framework for constructing G surfaces that interpolate data points on parallel cross sections, consisting of simple disjoined and non-nested contours, the number of which may vary from plane to plane. Using appropriately estimated cross tangent vectors at the given points, we split the problem into a sequence of local Hermite problems, each of which can be one of the follo...

We have studied the fractional and integer quantum Hall effect in high mobility double layer 2D hole gas systems. The large hole effective mass inhibits tunneling, allowing us to investigate the regime in which the interlayer and intralayer interactions are comparable without significant interlayer tunneling occurring. As the interlayer separation is reduced we observe the formation of bilayer ...

Dynamical correlation functions for temperature T = 0 are calculated for a Hubbard chain with infinite on-site repulsion. This chain contains three sites per unit cell and has a known resonating-valence-bond ground state for a filling of 2 particles per unit cell. A finite system of 24 sites is studied numerically. The recursion method is applied and results for spectral densities are compared ...

The Hubbard model on a two-leg ladder structure has been studied by a combination of series expansions at T = 0 and the density-matrix renormal-ization group. We report results for the ground state energy E 0 and spin-gap ∆ s at half-filling, as well as dispersion curves for one and two-hole excita-tions. For small U both E 0 and ∆ s show a dramatic drop near t/t ⊥ ∼ 0.5, which becomes more gra...

We use exact diagonalization techniques to study the interplay between strong correlations, superconductivity, and disorder in a model system. We study an extension of the t-J model by adding an infinite-range d-wave superconductivity inducing term and disorder. Our work shows that in the clean case the magnitude of the order parameter is surprisingly small for low-hole filling, thus implying t...

We have performed low-temperature transport experiments on a Si/SiGe hole system. The measured transverse and longitudinal conductivities σxx and σxy allows us to study the magnetic-field-induced transitions in the system. In particular, we present the first study of temperature-driven flow lines in the ”anomalous Hall insulator” regime near a Landau level filling factor ν = 1.5. The ”anomalous...