7,892 research outputs found
Topological phases and delocalization of quantum walks in random environments
We investigate one-dimensional (1D) discrete time quantum walks (QWs) with
spatially or temporally random defects as a consequence of interactions with
random environments. We focus on the QWs with chiral symmetry in a topological
phase, and reveal that chiral symmetry together with bipartite nature of the
QWs brings about intriguing behaviors such as coexistence of topologically
protected edge states at zero energy and Anderson transitions in the 1D chiral
class at non-zero energy in their dynamics. Contrary to the previous studies,
therefore, the spatially disordered QWs can avoid complete localization due to
the Anderson transition. It is further confirmed that the edge states are
robust for spatial disorder but not for temporal disorder.Comment: 7 pages, 7 figure
Mott transitions in two-orbital Hubbard systems
We investigate the Mott transitions in two-orbital Hubbard systems. Applying
the dynamical mean field theory and the self-energy functional approach, we
discuss the stability of itinerant quasi-particle states in each band. It is
shown that separate Mott transitions occur at different Coulomb interaction
strengths in general. On the other hand, if some special conditions are
satisfied for the interactions, spin and orbital fluctuations are equally
enhanced at low temperatures, resulting in a single Mott transition. The phase
diagrams are obtained at zero and finite temperatures. We also address the
effect of the hybridization between two orbitals, which induces the Kondo-like
heavy fermion states in the intermediate orbital-selective Mott phase.Comment: 21 Pages, 17 Figures, to appear in Progress of Theoretical Physics
(YKIS2004 Proceedings
Spin Chains with Periodic Array of Impurities
We investigate the spin chain model composed of periodic array of two kinds
of spins and , which allows us to study the spin chains with
impurities as well as the alternating spin chains in a unified fashion. By
using the Lieb-Shultz-Mattis theorem, we first study the model rigorously, and
then by mapping it to the non-linear sigma model, we extensively investigate
low-energy properties with particular emphasis on the competition between the
massive and massless phases.Comment: 5 pages, revtex, To appear in PR
Systematic Analysis of Frustration Effects in Anisotropic Checkerboard Lattice Hubbard Model
We study the ground state properties of the geometrically frustrated Hubbard
model on the anisotropic checkerboard lattice with nearest-neighbor hopping
and next nearest-neighbor hopping . By using the path-integral
renormalization group method, we study the phase diagram in the parameter space
of the Hubbard interaction and the frustration-control parameter .
Close examinations of the effective hopping, the double occupancy, the momentum
distribution and the spin/charge correlation functions allow us to determine
the phase diagram at zero temperature, where the plaquette-singlet insulator
emerges besides the antiferromagnetic insulator and the paramagnetic metal.
Spin-liquid insulating states without any kind of symmetry breaking cannot be
found in our frustrated model.Comment: 7pages, 5figure
Zero-temperature Phase Diagram of Two Dimensional Hubbard Model
We investigate the two-dimensional Hubbard model on the triangular lattice
with anisotropic hopping integrals at half filling. By means of a self-energy
functional approach, we discuss how stable the non-magnetic state is against
magnetically ordered states in the system. We present the zero-temperature
phase diagram, where the normal metallic state competes with magnetically
ordered states with and structures. It is shown
that a non-magnetic Mott insulating state is not realized as the ground state,
in the present framework, but as a meta-stable state near the magnetically
ordered phase with structure.Comment: 4 pages, 4 figure
Character Sequence Models for ColorfulWords
We present a neural network architecture to predict a point in color space
from the sequence of characters in the color's name. Using large scale
color--name pairs obtained from an online color design forum, we evaluate our
model on a "color Turing test" and find that, given a name, the colors
predicted by our model are preferred by annotators to color names created by
humans. Our datasets and demo system are available online at colorlab.us
Exact Drude weight for the one-dimensional Hubbard model at finite temperatures
The Drude weight for the one-dimensional Hubbard model is investigated at
finite temperatures by using the Bethe ansatz solution. Evaluating finite-size
corrections to the thermodynamic Bethe ansatz equations, we obtain the formula
for the Drude weight as the response of the system to an external gauge
potential. We perform low-temperature expansions of the Drude weight in the
case of half-filling as well as away from half-filling, which clearly
distinguish the Mott-insulating state from the metallic state.Comment: 9 pages, RevTex, To appear in J. Phys.
QUALITATIVE ANALYSIS ON THE VAPOR LOCKING VEHICLE BRAKE SYSTEMS
ArticleJournal of the Faculty of Textile Science and Technology, Shinshu University. Ser. B, Engineering 17: 1-15(1986)departmental bulletin pape
Renormalized Harmonic-Oscillator Description of Confined Electron Systems with Inverse-Square Interaction
An integrable model for SU() electrons with inverse-square interaction
is studied for the system with confining harmonic potential. We develop a new
description of the spectrum based on the {\it renormalized
harmonic-oscillators} which incorporate interaction effects via the repulsion
of energy levels. This approach enables a systematic treatment of the
excitation spectrum as well as the ground-state quantities.Comment: RevTex, 7 page
STUDIES ON BRAKING-WIND UP VIBRATIONS OF MOTOR VEHICLE AND ITS SKIDMARKS
ArticleJournal of the Faculty of Textile Science and Technology, Shinshu University. Ser. B, Engineering 15: 1-11(1982)departmental bulletin pape
- …