20,834 research outputs found
The Fractional Quantum Hall States at and and their Non-Abelian Nature
We investigate the nature of the fractional quantum Hall (FQH) state at
filling factor , and its particle-hole conjugate state at ,
with the Coulomb interaction, and address the issue of possible competing
states. Based on a large-scale density-matrix renormalization group (DMRG)
calculation in spherical geometry, we present evidence that the physics of the
Coulomb ground state (GS) at and is captured by the
parafermion Read-Rezayi RR state, . We first establish that the
state at is an incompressible FQH state, with a GS protected by a
finite excitation gap, with the shift in accordance with the RR state. Then, by
performing a finite-size scaling analysis of the GS energies for
with different shifts, we find that the state has the lowest
energy among different competing states in the thermodynamic limit. We find the
fingerprint of topological order in the FQH and
states, based on their entanglement spectrum and topological entanglement
entropy, both of which strongly support their identification with the
state. Furthermore, by considering the shift-free
infinite-cylinder geometry, we expose two topologically-distinct GS sectors,
one identity sector and a second one matching the non-Abelian sector of the
Fibonacci anyonic quasiparticle, which serves as additional evidence for the
state at and .Comment: 12 pages, 8 figure
Topological Characterization of Non-Abelian Moore-Read State using Density-Matrix Renormailzation Group
The non-Abelian topological order has attracted a lot of attention for its
fundamental importance and exciting prospect of topological quantum
computation. However, explicit demonstration or identification of the
non-Abelian states and the associated statistics in a microscopic model is very
challenging. Here, based on density-matrix renormalization group calculation,
we provide a complete characterization of the universal properties of bosonic
Moore-Read state on Haldane honeycomb lattice model at filling number
for larger systems, including both the edge spectrum and the bulk anyonic
quasiparticle (QP) statistics. We first demonstrate that there are three
degenerating ground states, for each of which there is a definite anyonic flux
threading through the cylinder. We identify the nontrivial countings for the
entanglement spectrum in accordance with the corresponding conformal field
theory. Through inserting the charge flux, it is found that two of the
ground states can be adiabatically connected through a fermionic
charge- QP being pumped from one edge to the other, while the
ground state in Ising anyon sector evolves back to itself. Furthermore, we
calculate the modular matrices and , which contain
all the information for the anyonic QPs. In particular, the extracted quantum
dimensions, fusion rule and topological spins from modular matrices positively
identify the emergence of non-Abelian statistics following the
Chern-Simons theory.Comment: 5 pages; 3 figure
Improved cosmological constraints on the curvature and equation of state of dark energy
We apply the Constitution compilation of 397 supernova Ia, the baryon
acoustic oscillation measurements including the parameter, the distance
ratio and the radial data, the five-year Wilkinson microwave anisotropy probe
and the Hubble parameter data to study the geometry of the universe and the
property of dark energy by using the popular Chevallier-Polarski-Linder and
Jassal-Bagla-Padmanabhan parameterizations. We compare the simple
method of joined contour estimation and the Monte Carlo Markov chain method,
and find that it is necessary to make the marginalized analysis on the error
estimation. The probabilities of and in the
Chevallier-Polarski-Linder model are skew distributions, and the marginalized
errors are ,
, , and
. For the Jassal-Bagla-Padmanabhan model, the
marginalized errors are ,
, , and
. The equation of state parameter of dark energy
is negative in the redshift range at more than level.
The flat CDM model is consistent with the current observational data
at the level.Comment: 10 figures, 12 pages, Classical and Quantum Gravity in press; v2 to
match the pulished versio
Probing the cosmic acceleration from combinations of different data sets
We examine in some detail the influence of the systematics in different data
sets including type Ia supernova sample, baryon acoustic oscillation data and
the cosmic microwave background information on the fitting results of the
Chevallier-Polarski-Linder parametrization. We find that the systematics in the
data sets does influence the fitting results and leads to different evolutional
behavior of dark energy. To check the versatility of Chevallier-Polarski-Linder
parametrization, we also perform the analysis on the Wetterich parametrization
of dark energy. The results show that both the parametrization of dark energy
and the systematics in data sets influence the evolutional behavior of dark
energy.Comment: 15 pages, 5 figures and 1 table, major revision, delete bao a data,
main results unchanged. jcap in press
Photon Momentum Transfer in Single-Photon Double Ionization of Helium
We theoretically and experimentally investigate the photon momentum transfer in single-photon double ionization of helium at various large photon energies. We find that the forward shifts of the momenta along the light propagation of the two photoelectrons are roughly proportional to their fraction of the excess energy. The mean value of the forward momentum is about 8/5 of the electron energy divided by the speed of light. This holds for fast and slow electrons despite the fact that the energy sharing is highly asymmetric and the slow electron is known to be ejected by secondary processes of shake off and knockout rather than directly taking its energy from the photon. The biggest deviations from this rule are found for the region of equal energy sharing where the quasifree mechanism dominates double ionization
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