24,044 research outputs found
Rotated stripe order and its competition with superconductivity in LaSrCuO
We report the observation of a bulk charge modulation in
LaSrCuO (LSCO) with a characteristic in-plane wave-vector
of (0.236, ), with =0.011 r.l.u. The transverse shift of
the ordering wave-vector indicates the presence of rotated charge-stripe
ordering, demonstrating that the charge ordering is not pinned to the Cu-O bond
direction. On cooling through the superconducting transition, we find an abrupt
change in the growth of the charge correlations and a suppression of the charge
order parameter indicating competition between the two orderings. Orthorhombic
LSCO thus helps bridge the apparent disparities between the behavior previously
observed in the tetragonal "214" cuprates and the orthorhombic yttrium and
bismuth-based cuprates and thus lends strong support to the idea that there is
a common motif to charge order in all cuprate families.Comment: 6 pages, 4 figue
Entanglement and spin squeezing in the two-atom Dicke model
We analyze the relation between the entanglement and spin-squeezing parameter
in the two-atom Dicke model and identify the source of the discrepancy recently
reported by Banerjee and Zhou et al that one can observe entanglement without
spin squeezing. Our calculations demonstrate that there are two criteria for
entanglement, one associated with the two-photon coherences that create
two-photon entangled states, and the other associated with populations of the
collective states. We find that the spin-squeezing parameter correctly predicts
entanglement in the two-atom Dicke system only if it is associated with
two-photon entangled states, but fails to predict entanglement when it is
associated with the entangled symmetric state. This explicitly identifies the
source of the discrepancy and explains why the system can be entangled without
spin-squeezing. We illustrate these findings in three examples of the
interaction of the system with thermal, classical squeezed vacuum and quantum
squeezed vacuum fields.Comment: 7 pages, 1 figur
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Neutrophils promote CXCR3-dependent itch in the development of atopic dermatitis.
Chronic itch remains a highly prevalent disorder with limited treatment options. Most chronic itch diseases are thought to be driven by both the nervous and immune systems, but the fundamental molecular and cellular interactions that trigger the development of itch and the acute-to-chronic itch transition remain unknown. Here, we show that skin-infiltrating neutrophils are key initiators of itch in atopic dermatitis, the most prevalent chronic itch disorder. Neutrophil depletion significantly attenuated itch-evoked scratching in a mouse model of atopic dermatitis. Neutrophils were also required for several key hallmarks of chronic itch, including skin hyperinnervation, enhanced expression of itch signaling molecules, and upregulation of inflammatory cytokines, activity-induced genes, and markers of neuropathic itch. Finally, we demonstrate that neutrophils are required for induction of CXCL10, a ligand of the CXCR3 receptor that promotes itch via activation of sensory neurons, and we find that that CXCR3 antagonism attenuates chronic itch
Coloron Phenomenology
A flavor-universal extension of the strong interactions was recently proposed
in response to the apparent excess of high- jets in the inclusive jet
spectrum measured at the Tevatron. This paper studies the color octet of
massive gauge bosons (`colorons') that is present in the low-energy spectrum of
the model's Higgs phase. Constraints from searches for new particles decaying
to dijets and from measurements of the weak-interaction parameter imply
that the colorons must have masses greater than 870-1000 GeV. The implications
of recent Tevatron data and the prospective input from future experiments are
also discussed.Comment: 13 pages, 4 embedded Postscript figures, LaTeX, full postscript
version also available at http://smyrd.bu.edu/htfigs/htfigs.html rectified
confusing phrase at end of sub-section on 'dijets
Influence of the single-particle Zeeman energy on the quantum Hall ferromagnet at high filling factors
In a recent paper [B. A. Piot et al., Phys. Rev. B 72, 245325 (2005)], we
have shown that the lifting of the electron spin degeneracy in the integer
quantum Hall effect at high filling factors should be interpreted as a
magnetic-field-induced Stoner transition. In this work, we extend the analysis
to investigate the influence of the single-particle Zeeman energy on the
quantum Hall ferromagnet at high filling factors. The single-particle Zeeman
energy is tuned through the application of an additional in-plane magnetic
field. Both the evolution of the spin polarization of the system and the
critical magnetic field for spin splitting are well described as a function of
the tilt angle of the sample in the magnetic field.Comment: Published in Phys. Rev.
Universal Static and Dynamic Properties of the Structural Transition in Pb(Zn1/3Nb2/3)O3
The relaxors Pb(ZnNb)O (PZN) and
Pb(MgNb)O (PMN) have very similar properties based on the
dielectric response around the critical temperature (defined by the
structural transition under the application of an electric field). It has been
widely believed that these materials are quite different below with the
unit cell of PMN remaining cubic while in PZN the low temperature unit cell is
rhombohedral in shape. However, this has been clarified by recent high-energy
x-ray studies which have shown that PZN is rhombohedral only in the skin while
the shape of the unit cell in the bulk is nearly cubic. In this study we have
performed both neutron elastic and inelastic scattering to show that the
temperature dependence of both the diffuse and phonon scattering in PZN and PMN
is very similar. Both compounds show a nearly identical recovery of the soft
optic mode and a broadening of the acoustic mode below . The diffuse
scattering in PZN is suggestive of an onset at the high temperature Burns
temperature similar to that in PMN. In contrast to PMN, we observe a broadening
of the Bragg peaks in both the longitudinal and transverse directions below
. We reconcile this additional broadening, not observed in PMN, in terms
of structural inhomogeneity in PZN. Based on the strong similarities between
PMN and PZN, we suggest that both materials belong to the same universality
class and discuss the relaxor transition in terms of the three-dimensional
Heisenberg model with cubic anisotropy in a random field.Comment: 11 pages, 10 figures. Updated version after helpful referee comment
Momentum-Resolved Charge Excitations in a Prototype One Dimensional Mott Insulator
We report momentum resolved charge excitations in a one dimensional (1-D)
Mott insulator studied using high resolution (~ 325 meV) inelastic x-ray
scattering over the entire Brillouin zone for the first time. Excitations at
the insulating gap edge are found to be highly dispersive (momentum
dependent)compared to excitations observed in two dimensional Mott insulators.
The observed dispersion in 1-D is consistent with charge excitations involving
holons which is unique to spin-1/2 quantum chain systems. These results point
to the potential utility of inelastic x-ray scattering in providing valuable
information about electronic structure of strongly correlated insulators.Comment: 3 pages, 2 figures, Revised with minor change
The transverse magnetoresistance of the two-dimensional chiral metal
We consider the two-dimensional chiral metal, which exists at the surface of
a layered, three-dimensional sample exhibiting the integer quantum Hall effect.
We calculate its magnetoresistance in response to a component of magnetic field
perpendicular to the sample surface, in the low temperature, but macroscopic,
regime where inelastic scattering may be neglected. The magnetoresistance is
positive, following a Drude form with a field scale,
, given by the transverse field strength at which
one quantum of flux, , passes through a rectangle with sides set by the
layer-spacing, , and the elastic mean free path, .
Experimental measurement of this magnetoresistance may therefore provide a
direct determination of the elastic mean free path in the chiral metal.Comment: submitted to Phys Rev
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