35,548 research outputs found
Dynamical Mean Field Theory for the Bose-Hubbard Model
The dynamical mean field theory (DMFT), which is successful in the study of
strongly correlated fermions, was recently extended to boson systems [Phys.
Rev. B {\textbf 77}, 235106 (2008)]. In this paper, we employ the bosonic DMFT
to study the Bose-Hubbard model which describes on-site interacting bosons in a
lattice. Using exact diagonalization as the impurity solver, we get the DMFT
solutions for the Green's function, the occupation density, as well as the
condensate fraction on a Bethe lattice. Various phases are identified: the Mott
insulator, the Bose-Einstein condensed (BEC) phase, and the normal phase. At
finite temperatures, we obtain the crossover between the Mott-like regime and
the normal phase, as well as the BEC-to-normal phase transition. Phase diagrams
on the plane and on the plane are
produced ( is the scaled hopping amplitude). We compare our results
with the previous ones, and discuss the implication of these results to
experiments.Comment: 11 pages, 8 figure
Expression of Green Fluorescence Protein (GFP) in Zebrafish Muscle through Injection: A Gene Therapy Model
Expression of the target gene is important for gene therapy. Presently, localized transgenesis is used for gene therapy which can be achieved by a target gene expression. Here, we have reported the plasmid mediated gene therapy to zebrafish model. For this purpose, we have chosen green fluorescent protein (GFP) as a target gene because the expression can be detected easily. GFP was inserted in a plasmid vector, pQE30 to develop the vector pQE30GFP. The plasmid pQE30GFP was constructed form plasmid, pQE30 and pEGFPC2. pQE30GFP injected directly in one group of fish into the muscle where luciferase expression was noted. In another group, after injection electroporation was performed where we have also noted luciferase expression; but, electroporation cause muscle injury to the zebrafish. In our case, the expression was very strong at the site of injection in first group in compare to electroporation group and in both the cases expression was stable more than two weeks
Bosonization Theory of Excitons in One-dimensional Narrow Gap Semiconductors
Excitons in one-dimensional narrow gap semiconductors of anti-crossing
quantum Hall edge states are investigated using a bosonization method. The
excitonic states are studied by mapping the problem into a non-integrable
sine-Gordon type model. We also find that many-body interactions lead to a
strong enhancement of the band gap. We have estimated when an exciton
instability may occur.Comment: 4pages, 1 figure, to appear in Phys. Rev. B Brief Report
Binding Transition in Quantum Hall Edge States
We study a class of Abelian quantum Hall (QH) states which are topologically
unstable (T-unstable). We find that the T-unstable QH states can have a phase
transition on the edge which causes a binding between electrons and reduces the
number of gapless edge branches. After the binding transition, the
single-electron tunneling into the edge gains a finite energy gap, and only
certain multi-electron co-tunneling (such as three-electron co-tunneling for
edges) can be gapless. Similar phenomenon also appear for edge state
on the boundary between certain QH states. For example edge on the boundary
between and states only allow three-electron co-tunneling at
low energies after the binding transition.Comment: 4 pages, RevTeX, 1 figur
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
One-dimensional Ising model built on small-world networks: competing dynamics
In this paper, we offer a competing dynamic analysis of the one-dimensional
Ising model built on the small-world network (SWN). Adding-type SWNs are
investigated in detail using a simplified Hamiltonian of mean-field nature, and
the result of rewiring-type is given because of the similarities of these two
typical networks. We study the dynamical processes with competing Glauber
mechanism and Kawasaki mechanism. The Glauber-type single-spin transition
mechanism with probability p simulates the contact of the system with a heat
bath and the Kawasaki-type dynamics with probability 1-p simulates an external
energy flux. By studying the phase diagram obtained in the present work, we can
realize some dynamical properties influenced by the small-world effect.Comment: 5 pages, one figure, accepted for publication in Physical Review
A new class of -d topological superconductor with topological classification
The classification of topological states of matter depends on spatial
dimension and symmetry class. For non-interacting topological insulators and
superconductors the topological classification is obtained systematically and
nontrivial topological insulators are classified by either integer or .
The classification of interacting topological states of matter is much more
complicated and only special cases are understood. In this paper we study a new
class of topological superconductors in dimensions which has
time-reversal symmetry and a spin conservation symmetry. We
demonstrate that the superconductors in this class is classified by
when electron interaction is considered, while the
classification is without interaction.Comment: 5 pages main text and 3 pages appendix. 1 figur
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