49,397 research outputs found
Spin dynamics in the antiferromagnetic phase for electron-doped cuprate superconductors
Based on the --- model we have calculated the dynamical spin
susceptibilities in the antiferromagnetic (AF) phase for electron-doped
cuprates, by use of the slave-boson mean-field theory and random phase
approximation. Various results for the susceptibilities versus energy and
momentum have been shown at different dopings. At low energy, except the
collective spin-wave mode around and 0, we have primarily observed
that new resonance peaks will appear around and equivalent
points with increasing doping, which are due to the particle-hole excitations
between the two AF bands. The peaks are pronounced in the transverse
susceptibility but not in the longitudinal one. These features are predicted
for neutron scattering measurements.Comment: 5 pages, 3 figures, published version with minor change
An Ultra-fast DOA Estimator with Circular Array Interferometer Using Lookup Table Method
The time-consuming phase ambiguity resolution makes the uniform circular array (UCA) interferometer not suitable for real-time direction-of-arrival (DOA) estimation. This paper introduces the lookup table (LUT) method to solve this problem. The key of the method is that we look up the ambiguity numbers instead of the eventual DOA from the table, and then the DOA is obtained by relatively small amount of calculation. This makes it possible that we are able to shrink the table size while maintain the DOA estimation accuracy. The table addresses cover all possible measured phase differences (PDs), which enables the method to be free of spatial scanning. Moreover, without adding frequency index to the lookup table, the estimator can realize wideband application. As an example, a field-programmable gate array (FPGA) based DOA estimator with the estimation time of 180 ns is presented, accompanied by the measured results. This method possesses the advantages of ultra-high speed, high accuracy and low memory usage
Phase diagram of doped BaFeAs superconductor under broken symmetry
We develop a minimal multiorbital tight-binding model with realistic hopping
parameters. The model breaks the symmetry of the tetragonal point group by
lowering it from to , which accurately describes the Fermi
surface evolution of the electron-doped BaFeCoAs and hole-doped
BaKFeAs compounds. An investigation of the phase diagram
with a mean-field -- Bogoliubov-de Gennes Hamiltonian results in
agreement with the experimentally observed electron- and hole-doped phase
diagram with only one set of , and parameters. Additionally, the
self-consistently calculated superconducting order parameter exhibits
-wave pairing symmetry with a small d-wave pairing admixture in the
entire doping range, % The superconducting -wave order parameter
which is the subtle result of the weakly broken symmetry and competing
interactions in the multiorbital mean-field Hamiltonian
Synthetic fabrication of nanoscale MoS₂-based transition metal sulfides
2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Multiphoton entanglement through a Bell multiport beam splitter
Multiphoton entanglement is an important resource for linear optics quantum
computing. Here we show that a wide range of highly entangled multiphoton
states, including W-states, can be prepared by interfering single photons
inside a Bell multiport beam splitter and using postselection. A successful
state preparation is indicated by the collection of one photon per output port.
An advantage of the Bell multiport beam splitter is that it redirects the
photons without changing their inner degrees of freedom. The described setup
can therefore be used to generate polarisation, time-bin and frequency
multiphoton entanglement, even when using only a single photon source.Comment: 8 pages, 2 figures, carefully revised version, references adde
Coexisting charge and magnetic orders in the dimer-chain iridate Ba5AlIr2O11
We have synthesized and studied single-crystal Ba5AlIr2O11 that features
dimer chains of two inequivalent octahedra occupied by tetravalent and
pentavalent ions, respectively. Ba5AlIr2O11 is a Mott insulator that undergoes
a subtle structural phase transition near 210 K and a magnetic transition at
4.5 K; the latter transition is surprisingly resistant to applied magnetic
fields up to 12 T, but sensitive to modest applied pressure. All results
indicate that the phase transition at 210 K signals an enhanced charge order
that induces electrical dipoles and strong dielectric response near 210 K. It
is clear that the strong covalency and spin-orbit interaction (SOI) suppress
double exchange in Ir dimers and stabilize a novel magnetic state. The behavior
of Ba5AlIr2O11 therefore provides unique insights into the physics of SOI along
with strong covalency in competition with double exchange interactions of
comparable strength.Comment: 6 figures, 20 pages. arXiv admin note: text overlap with
arXiv:1505.0087
Initial and Final State Interaction Effects in Small-x Quark Distributions
We study the initial and final state interaction effects in the transverse
momentum dependent parton distributions in the small- saturation region. In
particular, we discuss the quark distributions in the semi-inclusive deep
inelastic scattering, Drell-Yan lepton pair production and dijet-correlation
processes in collisions. We calculate the quark distributions in the
scalar-QED model and then extend to the color glass condensate formalism in
QCD. The quark distributions are found universal between the DIS and Drell-Yan
processes. On the other hand, the quark distribution from the
channel contribution to the dijet-correlation process is not universal.
However, we find that it can be related to the quark distribution in DIS
process by a convolution with the normalized unintegrated gluon distribution in
the color glass condensate formalism in the large limit.Comment: 20 pages, 6 figure
Single-qubit rotations in two-dimensional optical lattices with multiqubit addressing
Published versio
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