2,561 research outputs found
Graded Lie algebras with finite polydepth
If A is a graded connected algebra then we define a new invariant, polydepth
A, which is finite if for some A-module M of at most
polynomial growth. Theorem 1: If f : X \to Y is a continuous map of finite
category, and if the orbits of H_*(\Omega Y) acting in the homology of the
homotopy fibre grow at most polynomially, then H_*(\Omega Y) has finite
polydepth. Theorem 2: If L is a graded Lie algebra and polydepth UL is finite
then either L is solvable and UL grows at most polynomially or else for some
integer d and all r, , some
Proposed experiments to probe the non-abelian \nu=5/2 quantum Hall state
We propose several experiments to test the non-abelian nature of
quasi-particles in the fractional quantum Hall state of \nu=5/2. One set of
experiments studies interference contribution to back-scattering of current,
and is a simplified version of an experiment suggested recently. Another set
looks at thermodynamic properties of a closed system. Both experiments are only
weakly sensitive to disorder-induced distribution of localized quasi-particles.Comment: Additional references and an improved figure, 5 page
Anti-Fall: A Non-intrusive and Real-time Fall Detector Leveraging CSI from Commodity WiFi Devices
Fall is one of the major health threats and obstacles to independent living
for elders, timely and reliable fall detection is crucial for mitigating the
effects of falls. In this paper, leveraging the fine-grained Channel State
Information (CSI) and multi-antenna setting in commodity WiFi devices, we
design and implement a real-time, non-intrusive, and low-cost indoor fall
detector, called Anti-Fall. For the first time, the CSI phase difference over
two antennas is identified as the salient feature to reliably segment the fall
and fall-like activities, both phase and amplitude information of CSI is then
exploited to accurately separate the fall from other fall-like activities.
Experimental results in two indoor scenarios demonstrate that Anti-Fall
consistently outperforms the state-of-the-art approach WiFall, with 10% higher
detection rate and 10% less false alarm rate on average.Comment: 13 pages,8 figures,corrected version, ICOST conferenc
Correlation-hole induced paired quantum Hall states in lowest Landau level
A theory is developed for the paired even-denominator fractional quantum Hall
states in the lowest Landau level. We show that electrons bind to quantized
vortices to form composite fermions, interacting through an exact instantaneous
interaction that favors chiral p-wave pairing. Two canonically dual pairing gap
functions are related by the bosonic Laughlin wavefunction (Jastraw factor) due
to the correlation holes. We find that the ground state is the Moore-Read
pfaffian in the long wavelength limit for weak Coulomb interactions, a new
pfaffian of an oscillatory pairing function for intermediate interactions, and
a Read-Rezayi composite Fermi liquid beyond a critical interaction strength.
Our findings are consistent with recent experimental observations of the 1/2
and 1/4 fractional quantum Hall effects in asymmetric wide quantum wells.Comment: 4 pages, 2 figures; published versio
An alternative field theory for the Kosterlitz-Thouless transition
We extend a Gaussian model for the internal electrical potential of a
two-dimensional Coulomb gas by a non-Gaussian measure term, which singles out
the physically relevant configurations of the potential. The resulting
Hamiltonian, expressed as a functional of the internal potential, has a
surprising large-scale limit: The additional term simply counts the number of
maxima and minima of the potential. The model allows for a transparent
derivation of the divergence of the correlation length upon lowering the
temperature down to the Kosterlitz-Thouless transition point.Comment: final version, extended discussion, appendix added, 8 pages, no
figure, uses IOP documentclass iopar
Imaginary Squashing Mode Spectroscopy of Helium Three B
We have made precision measurements of the frequency of a collective mode of
the superfluid 3He-B order parameter, the J=2- imaginary squashing mode.
Measurements were performed at multiple pressures using interference of
transverse sound in an acoustic cavity. Transverse waves propagate in the
vicinity of this order parameter mode owing to off-resonant coupling. At the
crossing of the sound mode and the order parameter mode, the sound wave is
strongly attenuated. We use both velocity and attenuation measurements to
determine precise values of the mode frequency with a resolution between 0.1%
and 0.25%.Comment: 6 pages, 4 figures, submitted to proceedings of Quantum Fluids and
Solids (QFS) Conference 2006; revised 9/26/0
Enhancement of cholesterol esterification in aortic smooth muscle cells by medium of macrophages conditioned with acetylated LDL
Fractional quantum Hall effect at : Ground states, non-Abelian quasiholes, and edge modes in a microscopic model
We present a comprehensive numerical study of a microscopic model of the
fractional quantum Hall system at filling fraction , based on the
disc geometry. Our model includes Coulomb interaction and a semi-realistic
confining potential. We also mix in some three-body interaction in some cases
to help elucidate the physics. We obtain a phase diagram, discuss the
conditions under which the ground state can be described by the Moore-Read
state, and study its competition with neighboring stripe phases. We also study
quasihole excitations and edge excitations in the Moore-Read--like state. From
the evolution of edge spectrum, we obtain the velocities of the charge and
neutral edge modes, which turn out to be very different. This separation of
velocities is a source of decoherence for a non-Abelian quasihole/quasiparticle
(with charge ) when propagating at the edge; using numbers obtained
from a specific set of parameters we estimate the decoherence length to be
around four microns. This sets an upper bound for the separation of the two
point contacts in a double point contact interferometer, designed to detect the
non-Abelian nature of such quasiparticles. We also find a state that is a
potential candidate for the recently proposed anti-Pfaffian state. We find the
speculated anti-Pfaffian state is favored in weak confinement (smooth edge)
while the Moore-Read Pfaffian state is favored in strong confinement (sharp
edge).Comment: 15 pages, 9 figures; Estimate of e/4 quasiparticle/hole coherence
length when propagating along the edge modified in response to a recent
revision of Ref. 25, and minor changes elsewher
Composite Fermions with Orbital Magnetization
For quantum Hall systems, in the limit of large magnetic field (or
equivalently small electron band mass ), the static response of electrons
to a spatially varying magnetic field is largely determined by kinetic energy
considerations. This response is not correctly given in existing approximations
based on the Fermion Chern-Simons theory of the partially filled Landau level.
We remedy this problem by attaching an orbital magnetization to each fermion to
separate the current into magnetization and transport contributions, associated
with the cyclotron and guiding center motions respectively. This leads to a
Chern-Simons Fermi liquid description of the state which
correctly predicts the dependence of the static and dynamic response in
the limit .Comment: 4 pages, RevTeX, no figure
Thermopower as a Possible Probe of Non-Abelian Quasiparticle Statistics in Fractional Quantum Hall Liquids
We show in this paper that thermopower is enhanced in non-Abelian quantum
Hall liquids under appropriate conditions. This is because thermopower measures
entropy per electron in the clean limit, while the degeneracy and entropy
associated with non-Abelian quasiparticles enhance entropy when they are
present. Thus thermopower can potentially probe non-Abelian nature of the
quasiparticles, and measure their quantum dimension.Comment: 5 pages. Minor revisions in response to referee comments. Published
versio
- …