429 research outputs found
Detecting monopole charge in Weyl semimetals via quantum interference transport
Topological Weyl semimetals can host Weyl nodes with monopole charges in
momentum space. How to detect the signature of the monopole charges in quantum
transport remains a challenging topic. Here, we reveal the connection between
the parity of monopole charge in topological semimetals and the quantum
interference corrections to the conductivity. We show that the parity of
monopole charge determines the sign of the quantum interference correction,
with odd and even parity yielding the weak anti-localization and weak
localization effects, respectively. This is attributed to the Berry phase
difference between time-reversed trajectories circulating the Fermi sphere that
encloses the monopole charges. From standard Feynman diagram calculations, we
further show that the weak-field magnetoconductivity at low temperatures is
proportional to in double-Weyl semimetals and in Weyl
semimetals, respectively, which could be verified experimentally.Comment: published versio
Detecting Lensing-Induced Diffraction in Astrophysical Gravitational Waves
Gravitational waves emitted from compact binary coalescence can be subject to
wave diffraction if they are gravitationally lensed by an intervening mass
clump whose Schwarzschild timescale matches the wave period. Waves in the
ground-based frequency band --Hz are sensitive to clumps with
masses -- enclosed within the impact parameter.
These can be the central parts of low mass --
dark matter halos, which are predicted in Cold Dark Matter scenarios but are
challenging to observe. Neglecting finely-tuned impact parameters, we focus on
lenses aligned generally on the Einstein scale for which multiple lensed images
may not form in the case of an extended lens. In this case, diffraction induces
amplitude and phase modulations whose sizes -- are small
enough so that standard matched filtering with unlensed waveforms do not
degrade, but are still detectable for events with high signal-to-noise ratio.
We develop and test an agnostic detection method based on dynamic programming,
which does not require a detailed model of the lensed waveforms. For
pseudo-Jaffe lenses aligned up to the Einstein radius, we demonstrate that a
pair of fully upgraded aLIGO/Virgo detectors can extract diffraction imprints
from binary black hole mergers out to --. The prospect will
improve dramatically for a third-generation detector for which binary black
hole mergers out to -- will all become valuable sources.Comment: 14 pages including references; 8 figures; comments are welcom
Transverse electric current induced by optically injected spin current in cross-shaped InGaAs/InAlAs system
We examine electric response of a linearly polarized light normally shed on a
cross-shaped quasi 2-dimensional InGaAs/InAlAs system with structure inversion
asymmetry. The photo-excited conduction electrons carry a pure spin current
with in-plane spin polarization due to the Rashba spin-orbit interaction. We
use Landauer-B\"{u}ttiker formalism to show that this spin current induces two
inward or outward transverse charge currents, which are observable in
experiments. This effect may serve as an experimental probe of certain types of
spin current.Comment: 5 pages, 3 figure
Dependability and Security in Medical Information System
This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Medical Information Systems (MIS) help medical practice and health care significantly. Security and dependability are two increasingly important factors for MIS nowadays. In one hand, people would be willing to step into the MIS age only when their privacy and integrity can be protected and guaranteed with MIS systems. On the other hand, only secure and reliable MIS systems would provide safe and solid medical and health care service to people. In this paper, we discuss some new security and reliability technologies which are necessary for and can be integrated with existing MISs and make the systems highly secure and dependable. We also present an implemented Middleware architecture which has been integrated with the existing VISTA/CPRS system in the U.S. Department of Veterans Affairs seamlessly and transparently
5-Bromo-4-iodo-2-methylÂaniline
The asymmetric unit of the title compound, C7H7BrIN, contains two independent molÂecules, which are linked by weak N—H⋯N hydroÂden-bonding interÂactions between the amino groups
Theoretical Evidence for the Berry-Phase Mechanism of Anomalous Hall Transport: First-principles Studies on CuCrSeBr
To justify the origin of anomalous Hall effect (AHE), it is highly desirable
to have the system parameters tuned continuously. By quantitative calculations,
we show that the doping dependent sign reversal in
CuCrSeBr, observed but not understood, is nothing but
direct evidence for the Berry-Phase mechanism of AHE. The systematic
calculations well explain the experiment data for the whole doping range where
the impurity scattering rates is changed by several orders with Br
substitution. Further sign change is also predicted, which may be tested by
future experiments.Comment: 4 page
Strong Gravitational Lensing of Gravitational Waves with TianQin
When gravitational waves pass by a massive object on its way to the Earth,
strong gravitational lensing effect will happen. Thus the GW signal will be
amplified, deflected, and delayed in time. Through analysing the lensed GW
waveform, physical properties of the lens can be inferred. On the other hand,
neglecting lensing effects in the analysis of GW data may induce systematic
errors in the estimating of source parameters. As a space-borne GW detector,
TianQin will be launched in the 2030s. It is expected to detect dozens of MBHBs
merger as far as z = 15, and thus will have high probability to detect at least
one lensed event during the mission lifetime. In this article, we discuss the
capability of TianQin to detect lensed MBHBs signals. Three lens models are
considered in this work: the point mass model, the SIS model, and the NFW
model. The sensitive frequency band for space-borne GW detectors is around
milli-hertz, and the corresponding GW wavelength could be comparable to the
lens gravitational length scale, which requires us to account for wave
diffraction effects. In calculating lensed waveforms, we adopt the
approximation of geometric optics at high frequencies to accelerate
computation, while precisely evaluate the diffraction integral at low
frequencies. Through a Fisher analysis, we analyse the accuracy to estimate the
lens parameters. We find that the accuracy can reach to the level of 10^-3 for
the mass of point mass and SIS lens, and to the level of 10^-5 for the density
of NFW lens. We also assess the impact on the accurate of estimating the source
parameters, and find that the improvement of the accuracy is dominated by the
increasing of SNR.Comment: 12 pages, 8 figure
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