17,537 research outputs found
The transport properties of Floquet topological superconductors at the transition from the topological phase to the Anderson localized phase
The Floquet topological superconducting state is a nonequilibrium
time-periodic state hosting Majorana fermions. We study its transport
properties by using the Kitaev model with time-periodic incommensurate
potentials, which experiences phase transition from the Floquet topological
superconducting phase to the Anderson localized phase with increasing driving
strength. We study both the real time dynamics of the current and the
non-analytic behavior of the tunneling conductance at the transition.
Especially, we find that the tunneling conductance changes continuously at the
transition, being a finite value in the presence of Floquet Majorana fermions,
but dropping to zero as the Majorana fermions vanish. For a special choice of
parameters, the Majorana fermions revive at larger driving strength,
accompanied by the revival of conductances.Comment: 8 pages, 5 figure
Lensed Arcs and Inner Structure of Abell 697
We present new optical observations of the z=0.282 cluster Abell 697 from the
Keck II telescope. Images show an unusual disturbed structure in the cD halo
and a previously unknown faint gravitational lens arc. A spectrum of the arc
did not yield a redshift, but its spectrum and colors suggest it lies at z>1.3.
We construct models to reproduce the arc that show the potential is likely to
be highly elliptical. We suggest that this cluster may have undergone a recent
merger and is in the process of forming its cD galaxy. Analysis of X-ray data
from ROSAT and ASCA suggests that the merging process is sufficiently advanced
that the gas in the cluster has relaxed, and A697 lies near the L_x-T_x
relation for normal clusters.Comment: LaTeX; 12 pages, 3 figures, submitted to ApJ Letter
Higgs amplitude mode in massless Dirac fermion systems
The Higgs amplitude mode in superconductors is the condensed matter analogy
of Higgs bosons in particle physics. We investigate the time evolution of Higgs
amplitude mode in massless Dirac systems, induced by a weak quench of an
attractive interaction. We find that the Higgs amplitude mode in the
half-filling honeycomb lattice has a logarithmic decaying behaviour,
qualitatively different from the decay in the normal
superconductors. Our study is also extended to the doped cases in honeycomb
lattice. As for the 3D Dirac semimetal at half filling, we obtain an undamped
oscillation of the amplitude mode. Our finding is not only an important
supplement to the previous theoretical studies on normal fermion systems, but
also provide an experimental signature to characterize the superconductivity in
2D or 3D Dirac systems.Comment: 6 pages, 8 figure
Evolution of Surface Deformations of Weakly-Bound Nuclei in the Continuum
We study weakly-bound deformed nuclei based on the coordinate-space Skyrme
Hartree-Fock-Bogoliubov approach, in which a large box is employed for treating
the continuum and surface diffuseness. Approaching the limit of core-halo
deformation decoupling, calculations found an exotic "egg"-like structure
consisting of a spherical core plus a prolate halo in Ne, in which the
resonant continuum plays an essential role. Generally the halo probability and
the decoupling effect in heavy nuclei are reduced compared to light nuclei, due
to denser level densities around Fermi surfaces. However, deformed halos in
medium-mass nuclei are possible with sparse levels of negative parity, for
example, in Ge. The surface deformations of pairing density
distributions are also influenced by the decoupling effect and are sensitive to
the effective pairing Hamiltonian.Comment: 5 pages and 5 figure
Weaving quantum optical frequency combs into continuous-variable hypercubic cluster states
Cluster states with higher-dimensional lattices that cannot be physically
embedded in three-dimensional space have important theoretical interest in
quantum computation and quantum simulation of topologically ordered
condensed-matter systems. We present a simple, scalable, top-down method of
entangling the quantum optical frequency comb into hypercubic-lattice
continuous-variable cluster states of a size of about 10^4 quantum field modes,
using existing technology. A hypercubic lattice of dimension D (linear, square,
cubic, hypercubic, etc.) requires but D optical parametric oscillators with
bichromatic pumps whose frequency splittings alone determine the lattice
dimensionality and the number of copies of the state.Comment: 8 pages, 5 figures, submitted for publicatio
Generalized Second-Order Thomas-Fermi Method for Superfluid Fermi Systems
Using the -expansion of the Green's function of the
Hartree-Fock-Bogoliubov equation, we extend the second-order Thomas-Fermi
approximation to generalized superfluid Fermi systems by including the
density-dependent effective mass and the spin-orbit potential. We first
implement and examine the full correction terms over different energy intervals
of the quasiparticle spectra in calculations of finite nuclei. Final
applications of this generalized Thomas-Fermi method are intended for various
inhomogeneous superfluid Fermi systems.Comment: 8 pages, 10 figures, PR
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