41,623 research outputs found
Peculiar Behavior of Si Cluster Ions in Solid Al
A peculiar ion behavior is found in a Si cluster, moving with a speed of
~0.22c (c: speed of light) in a solid Al plasma: the Si ion, moving behind the
forward moving Si ion closely in a several angstrom distance in the cluster,
feels the wake field generated by the forward Si. The interaction potential on
the rear Si may balance the deceleration backward force by itself with the
acceleration forward force by the forward Si in the longitudinal moving
direction. The forward Si would be decelerated normally. However, the
deceleration of the rear Si, moving behind closely, would be reduced
significantly, and the rear Si may catch up and overtake the forward moving Si
in the cluster during the Si cluster interaction with the high-density Al
plasma
Multiband effects on the conductivity for a multiband Hubbard model
The newly discovered iron-based superconductors have attracted lots of
interests, and the corresponding theoretical studies suggest that the system
should have six bands. In this paper, we study the multiband effects on the
conductivity based on the exact solutions of one-dimensional two-band Hubbard
model. We find that the orbital degree of freedom might enhance the critical
value of on-site interaction of the transition from a metal to an
insulator. This observation is helpful to understand why undoped High-
superconductors are usually insulators, while recently discovered iron-based
superconductors are metal. Our results imply that the orbital degree of freedom
in the latter cases might play an essential role.Comment: 4 pages, 5 figure
Fermionic concurrence in the extended Hubbard dimer
In this paper, we introduce and study the fermionic concurrence in a two-site
extended Hubbard model. Its behaviors both at the ground state and finite
temperatures as function of Coulomb interaction (on-site) and
(nearest-neighbor) are obtained analytically and numerically. We also
investigate the change of the concurrence under a nonuniform field, including
local potential and magnetic field, and find that the concurrence can be
modulated by these fields.Comment: 5 pages, 7 figure
Entanglement from density measurements: analytical density-functional for the entanglement of strongly correlated fermions
We derive an analytical density functional for the single-site entanglement
of the one-dimensional homogeneous Hubbard model, by means of an approximation
to the linear entropy. We show that this very simple density functional
reproduces quantitatively the exact results. We then use this functional as
input for a local density approximation to the single-site entanglement of
inhomogeneous systems. We illustrate the power of this approach in a
harmonically confined system, which could simulate recent experiments with
ultracold atoms in optical lattices as well as in a superlattice and in an
impurity system. The impressive quantitative agreement with numerical
calculations -- which includes reproducing subtle signatures of the particle
density stages -- shows that our density-functional can provide entanglement
calculations for actual experiments via density measurements. Next we use our
functional to calculate the entanglement in disordered systems. We find that,
at contrast with the expectation that disorder destroys the entanglement, there
exist regimes for which the entanglement remains almost unaffected by the
presence of disordered impurities.Comment: 6 pages, 3 figure
Tidal Waves -- a non-adiabatic microscopic description of the yrast states in near-spherical nuclei
The yrast states of nuclei that are spherical or weakly deformed in their
ground states are described as quadrupole waves running over the nuclear
surface, which we call "tidal waves". The energies and E2 transition
probabilities of the yrast states in nuclides with = 44, 46, 48 and are calculated by means of the cranking model in a microscopic
way. The nonlinear response of the nucleonic orbitals results in a strong
coupling between shape and single particle degrees of freedom
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