52,226 research outputs found
Scaling Between Periodic Anderson and Kondo Lattice Models
Continuous-Time Quantum Monte Carlo (CT-QMC) method combined with Dynamical
Mean Field Theory (DMFT) is used to calculate both Periodic Anderson Model
(PAM) and Kondo Lattice Model (KLM). Different parameter sets of both models
are connected by the Schrieffer-Wolff transformation. For degeneracy N=2, a
special particle-hole symmetric case of PAM at half filling which always fixes
one electron per impurity site is compared with the results of the KLM. We find
a good mapping between PAM and KLM in the limit of large on-site Hubbard
interaction U for different properties like self-energy, quasiparticle residue
and susceptibility. This allows us to extract quasiparticle mass
renormalizations for the f electrons directly from KLM. The method is further
applied to higher degenerate case and to realsitic heavy fermion system CeRhIn5
in which the estimate of the Sommerfeld coefficient is proven to be close to
the experimental value
Entanglement changing power of two-qubit unitary operations
We consider a two-qubit unitary operation along with arbitrary local unitary
operations acts on a two-qubit pure state, whose entanglement is C_0. We give
the conditions that the final state can be maximally entangled and be
non-entangled. When the final state can not be maximally entangled, we give the
maximal entanglement C_max it can reach. When the final state can not be
non-entangled, we give the minimal entanglement C_min it can reach. We think
C_max and C_min represent the entanglement changing power of two-qubit unitary
operations. According to this power we define an order of gates.Comment: 11 page
Phase equilibrium in two orbital model under magnetic field
The phase equilibrium in manganites under magnetic field is studied using a
two orbital model, based on the equivalent chemical potential principle for the
competitive phases. We focus on the magnetic field induced melting process of
CE phase in half-doped manganites. It is predicted that the homogenous CE phase
begins to decompose into coexisting ferromagnetic phase and CE phase once the
magnetic field exceeds the threshold field. In a more quantitative way, the
volume fractions of the two competitive phases in the phase separation regime
are evaluated.Comment: 4 pages, 4 figure
Algebraic approach to the Hulthen potential
In this paper the energy eigenvalues and the corresponding eigenfunctions are
calculated for Hulthen potential. Then we obtain the ladder operators and show
that these operators satisfy SU(2) commutation relation.Comment: 8 Pages, 1 Tabl
Nonlinear Basis Pursuit
In compressive sensing, the basis pursuit algorithm aims to find the sparsest
solution to an underdetermined linear equation system. In this paper, we
generalize basis pursuit to finding the sparsest solution to higher order
nonlinear systems of equations, called nonlinear basis pursuit. In contrast to
the existing nonlinear compressive sensing methods, the new algorithm that
solves the nonlinear basis pursuit problem is convex and not greedy. The novel
algorithm enables the compressive sensing approach to be used for a broader
range of applications where there are nonlinear relationships between the
measurements and the unknowns
Heavy and Light Quarks with Lattice Chiral Fermions
The feasibility of using lattice chiral fermions which are free of
errors for both the heavy and light quarks is examined. The fact that the
effective quark propagators in these fermions have the same form as that in the
continuum with the quark mass being only an additive parameter to a chirally
symmetric antihermitian Dirac operator is highlighted. This implies that there
is no distinction between the heavy and light quarks and no mass dependent
tuning of the action or operators as long as the discretization error is negligible. Using the overlap fermion, we find that the
(and ) errors in the dispersion relations of the pseudoscalar and
vector mesons and the renormalization of the axial-vector current and scalar
density are small. This suggests that the applicable range of may be
extended to with only 5% error, which is a factor of
larger than that of the improved Wilson action. We show that the generalized
Gell-Mann-Oakes-Renner relation with unequal masses can be utilized to
determine the finite errors in the renormalization of the matrix elements
for the heavy-light decay constants and semileptonic decay constants of the B/D
meson.Comment: final version to appear in Int. Jou. Mod. Phys.
Quantum criticality and nodal superconductivity in the FeAs-based superconductor KFe2As2
The in-plane resistivity and thermal conductivity of
FeAs-based superconductor KFeAs single crystal were measured down to 50
mK. We observe non-Fermi-liquid behavior at =
5 T, and the development of a Fermi liquid state with when
further increasing field. This suggests a field-induced quantum critical point,
occurring at the superconducting upper critical field . In zero field
there is a large residual linear term , and the field dependence of
mimics that in d-wave cuprate superconductors. This indicates that
the superconducting gaps in KFeAs have nodes, likely d-wave symmetry.
Such a nodal superconductivity is attributed to the antiferromagnetic spin
fluctuations near the quantum critical point.Comment: 4 pages, 4 figures - replaces arXiv:0909.485
- …