40,405 research outputs found
Spatial interferences in the electron transport of heavy fermion materials
The scanning tunneling microscopy/spectroscopy and the point contact
spectroscopy represent one of the major progresses in recent heavy fermion
research. Both have revealed important information on the composite nature of
the emergent heavy electron quasiparticles. However, a detailed and thorough
microscopic understanding of the similarities and differences in the underlying
physical processes of these techniques is still lacking. Here we study the
electron transport in the normal state of the periodic Anderson lattice by
using the Keldysh nonequilibrium Green's function technique. In addition to the
well-known Fano interference between the conduction and f-electron channels,
our results further reveal the effect of spatial interference between different
spatial paths at the interface on the differential conductance and their
interesting interplay with the band features such as the hybridization gap and
the Van Hove singularity. We find that the spatial interference leads to a
weighted average in the momentum space for the electron transport and could
cause suppression of the electronic band features under certain circumstances.
In particular, it reduces the capability of probing the f-electron spectral
weight near the edges of the hybridization gap for large interface depending on
the Fermi surface of the lead. Our results indicates an intrinsic inefficiency
of the point contact spectroscopy in probing the f-electrons.Comment: 13 pages, 8 figures; with additional argument that PCS may
overestimate the hybridization gap as observed in SmB
The criterion for maximally entangled four-qubit state
Paolo Facchi et al.[Phys. Rev. A. 77, 060304(R) (2009)] presented a maximally
multipartite entangled state(MMES). Here we give the criterion for four-qubit
state.and some new characterizations of the maximally entangled four-qubit
state are given.Comment: 8 page
The Emerging Features of Bipolar Magnetic Regions during Solar Minima
Solar magnetic synoptic charts obtained by NSO/Kitt Peak and SOHO/MDI are
analyzed for studying the appearance of bipolar magnetic regions (BMRs) during
solar minima. As a result, we find the emergence of long-lived BMRs has three
typical features. (1) BMRs' emerging rates of the new cycles increase about 3
times faster than those of the old cycles decrease. (2) Two consecutive solar
cycles have an overlapping period of near 10 Carrington rotations. During this
very short overlapping time interval, BMRs of two cycles tend to concentrate in
the same longitudes. (3) About 53% BMRs distribute with a longitudinal distance
of 1/8 solar rotation. Such phenomenon suggests a longitudinal mode of m=8
existing during solar minima.Comment: 5 figures, 1 table, accepted by Ap
Thermodynamics of the - transition in cerium studied by an LDA + Gutzwiller method
The - transition in cerium has been studied in both zero and
finite temperature by Gutzwiller density functional theory. We find that the
first order transition between and phases persists to the
zero temperature with negative pressure. By further including the entropy
contributed by both electronic quasi-particles and lattice vibration, we obtain
the total free energy at given volume and temperature, from which we obtain the
- transition from the first principle calculation. We also
computed the phase diagram and pressure versus volume isotherms of cerium at
finite temperature and pressure, finding excellent agreement with the
experiments. Our calculation indicate that both the electronic entropy and
lattice vibration entropy plays important role in the -
transition.Comment: 5 pages, 4 figure
Gravitational waves induced by spinor fields
In realistic model-building, spinor fields with various masses are present.
During inflation, spinor field may induce gravitational waves as a second order
effect. In this paper, we calculate the contribution of single massive spinor
field to the power spectrum of primordial gravitational wave by using retarded
Green propagator. We find that the correction is scale-invariant and of order
for arbitrary spinor mass . Additionally, we also observe
that when , the dependence of correction on is
nontrivial.Comment: 16 pages, 1 figur
Probing charge correlations of quark gluon plasma by identified two-hadron rapidity correlations in ultra-relativistic AA collisions
We propose a new kind of two-particle correlation of identified hadrons in
longitudinal rapidity space, called ,
which can reflect clearly the charge correlations of hot quark system produced
in AA collisions at LHC energies. It is derived from the basic scenario of
quark combination mechanism of hadron production. Like the elliptic flow of
identified hadrons at intermediate transverse momentum, this correlation is
independent of the absolute hadronic yields but dependent only on the flavor
compositions of hadrons, and thus exhibits interesting properties for different
kinds of hadron species. We suggest the measurement of this observable in AA
collisions at LHC to gain more insights into the charge correlation properties
of produced hot quark matter.Comment: 4 pages, 1 figur
Quantum search by partial adiabatic evolution
A quantum search algorithm based on the partial adiabatic
evolution\cite{Tulsi2009} is provided. We calculate its time complexity by
studying the Hamiltonian in a two-dimensional Hilbert space. It is found that
the algorithm improves the time complexity, which is , of the
local adiabatic search algorithm\cite{Roland2002}, to
A Subpixel Registration Algorithm for Low PSNR Images
This paper presents a fast algorithm for obtaining high-accuracy subpixel
translation of low PSNR images. Instead of locating the maximum point on the
upsampled images or fitting the peak of correlation surface, the proposed
algorithm is based on the measurement of centroid on the cross correlation
surface by Modified Moment method. Synthetic images, real solar images and
standard testing images with white Gaussian noise added were tested, and the
results show that the accuracies of our algorithm are comparable with other
subpixel registration techniques and the processing speed is higher. The
drawback is also discussed at the end of this paper.Comment: in 2012 IEEE 5th Int. Conf. on Advanced Computational Intelligence
(ICACI) (New York: IEEE), 62
Uncertainty equalities and uncertainty relation in weak measurement
Uncertainty principle is one of the fundamental principles of quantum
mechanics. In this work, we derive two uncertainty equalities, which hold for
all pairs of incompatible observables. We also obtain an uncertainty relation
in weak measurement which captures the limitation on the preparation of pre-
and post-selected ensemble and hold for two non-Hermitian operators
corresponding to two non-commuting observables.Comment: 4 page
Investigation of Umbral Dots with the New Vacuum Solar Telescope
Umbral dots (UDs) are small isolated brightenings observed in sunspot umbrae.
They are convective phenomena existing inside umbrae. UDs are usually divided
into central UDs (CUDs) and peripheral UDs (PUDs) according to their positions
inside an umbra. Our purpose is to investigate UD properties and analyze their
relationships, and further to find whether or not the properties depend on
umbral magnetic field strengths. Thus, we selected high-resolution TiO images
of four active regions (ARs) taken under the best seeing conditions with the
\textit{New Vacuum Solar Telescope} in the Fuxian Solar Observatory of the
Yunnan Astronomical Observatory, China. The four ARs (NOAA 11598, 11801, 12158,
and 12178) include six sunspots. A total of 1220 CUDs and 603 PUDs were
identified. Meanwhile, the radial component of the vector magnetic field of the
sunspots taken with the \textit{Helioseismic and Magnetic Imager} on-board the
\textit{Solar Dynamics Observatory} was used to analyze relationships between
UD properties and umbral magnetic field strengths. We find that diameters and
lifetimes of UDs exhibit an increasing trend with the brightness, but
velocities do not. Moreover, diameters, intensities, lifetimes and velocities
depend on the surrounding magnetic field. A CUD diameter was found larger, the
CUD brighter, its lifetime longer, and its motion slower in a weak umbral
magnetic field environment than in a strong one.Comment: 16 Pages, 7 Figures, and 5 Tables, accepted for publication in Solar
Physic
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