3,322 research outputs found
Holographic storage of multiple coherence gratings in a Bose-Einstein condensate
We demonstrate superradiant conversion between a two-mode collective atomic
state and a single-mode light field in an elongated cloud of Bose-condensed
atoms. Two off-resonant write beams induce superradiant Raman scattering,
producing two independent coherence gratings with a different wave vector in
the cloud. By applying phase-matched read beams after a controllable delay, the
gratings can be selectively converted into the light field also in a
superradiant way. Due to the large cooperativity parameter and the small
velocity width of the condensate, a high conversion efficiency of % and
a long storage time of s were achieved.Comment: 5 pages, 4 figure
Effective theories of gauge-Higgs unification models in warped spacetime
We derive four-dimensional (4D) effective theories of the gauge-Higgs
unification models in the warped spacetime. The effective action can be
expressed in a simple form by neglecting subleading corrections to the wave
functions. We have shown in our previous works that some Higgs couplings to the
other fields are suppressed by factors that depend on from the
values in the standard model. Here is the Wilson line phase
along the fifth dimension, which characterizes the electroweak symmetry
breaking. The effective action derived here explicitly shows a nonlinear
structure of the Higgs sector, which clarifies the origins of those suppression
factors.Comment: 36 pages, 1 figur
Solving the Master Equation for Extremely Long Time Scale Calculations
The dynamics of magnetic reversal process plays an important role in the
design of the magnetic recording devices in the long time scale limit. In
addition to long time scale, microscopic effects such as the entropic effect
become important in magnetic nano-scale systems. Many advanced simulation
methods have been developed, but few have the ability to simulate the long time
scale limit and to accurately model the microscopic effects of nano-scale
systems at the same time. We develop a new Monte Carlo method for calculating
the dynamics of magnetic reversal at arbitrary long time. For example, actual
calculations were performed up to 1e50 Monte Carlo steps. This method is based
on microscopic interactions of many constituents and the master equation for
magnetic probability distribution function is solved symbolically.Comment: accepted for publication in Computer Physics and Communication
Onset of intruder ground state in exotic Na isotopes and evolution of the N=20 shell gap
The onset of intruder ground states in Na isotopes is investigated by
comparing experimental data and shell-model calculations. This onset is one of
the consequences of the disappearance of the N=20 magic structure, and the Na
isotopes are shown to play a special role in clarifying the change of this
magic structure. Both the electromagnetic moments and the energy levels clearly
indicate an onset of ground state intruder configurations at neutron number
N=19 already, which arises only with a narrow N=20 shell gap in Na isotopes
resulting from the spin-isospin dependence of the nucleon-nucleon interaction
(as compared to a wider gap in stable nuclei like 40Ca). It is shown why the
previous report based on the mass led to a wrong conclusion.Comment: 9 pages, 6 figures, to be published in Phys. Rev.
Direct Mediation of Meta-Stable Supersymmetry Breaking
The supersymmetric SU(Nc) Yang-Mills theory coupled to Nf matter fields in
the fundamental representation has meta-stable vacua with broken supersymmetry
when Nc < Nf < 3/2 Nc. By gauging the flavor symmetry, this model can be
coupled directly to the standard model. We show that it is possible to make a
slight deformation to the model so that gaugino masses are generated and the
Landau pole problem can be avoided. The deformed model has simple realizations
on intersecting branes in string theory, where various features of the
meta-stable vacua are encoded geometrically as brane configurations.Comment: 22 pages, 4 figures, a reference added, version to appear in PR
Strong Turbulence in the Cool Cores of Galaxy Clusters: Can Tsunamis Solve the Cooling Flow Problem?
Based on high-resolution two-dimensional hydrodynamic simulations, we show
that the bulk gas motions in a cluster of galaxies, which are naturally
expected during the process of hierarchical structure formation of the
universe, have a serous impact on the core. We found that the bulk gas motions
represented by acoustic-gravity waves create local but strong turbulence, which
reproduces the complicated X-ray structures recently observed in cluster cores.
Moreover, if the wave amplitude is large enough, they can suppress the
radiative cooling of the cores. Contrary to the previous studies, the heating
is operated by the turbulence, not weak shocks. The turbulence could be
detected in near-future space X-ray missions such as ASTRO-E2.Comment: Movies are available at http://th.nao.ac.jp/tsunami/index.ht
Advantages of nonclassical pointer states in postselected weak measurements
We investigate, within the weak measurement theory, the advantages of
non-classical pointer states over semi-classical ones for coherent, squeezed
vacuum, and Schr\"{o}inger cat states. These states are utilized as pointer
state for the system operator with property ,
where represents the identity operator. We calculate the ratio
between the signal-to-noise ratio (SNR) of non-postselected and postselected
weak measurements. The latter is used to find the quantum Fisher information
for the above pointer states. The average shifts for those pointer states with
arbitrary interaction strength are investigated in detail. One key result is
that we find the postselected weak measurement scheme for non-classical pointer
states to be superior to semi-classical ones. This can improve the precision of
measurement process.Comment: 8 pages, 5 figure
Efficacy of combined peroxisome proliferator-activated receptor-α ligand and glucocorticoid therapy in a murine model of atopic dermatitis.
Although topical glucocorticoids (GCs) show potent anti-inflammatory activity in inflamed skin, they can also exert numerous harmful effects on epidermal structure and function. In contrast, topical applications of ligands of peroxisome proliferator-activated receptor-α (PPARα) not only reduce inflammation but also improve cutaneous barrier homeostasis. Therefore, we examined whether sequential topical GCs followed by topical Wy14643 (a ligand of PPARα) might be more effective than either alone for atopic dermatitis (AD) in a hapten (oxazolone (Ox))-induced murine model with multiple features of AD (Ox-AD). Despite expected anti-inflammatory benefits, topical GC alone induced (i) epidermal thinning; (ii) reduced expression of involucrin, loricrin, and filaggrin; and (iii) allowed outside-to-inside penetration of an epicutaneous tracer. Although Wy14643 alone yielded significant therapeutic benefits in mice with mild or moderate Ox-AD, it was less effective in severe Ox-AD. Yet, topical application of Wy14643 after GC was not only significantly effective comparable with GC alone, but it also prevented GC-induced structural and functional abnormalities in permeability barrier homeostasis. Moreover, rebound flares were largely absent after sequential treatment with GC and Wy14643. Together, these results show that GC and PPARα ligand therapy together is not only effective but also prevents development of GC-induced side effects, including rebound flares, in murine AD
Magnetic structure and spin dynamics of quasi-one-dimensional spin-chain antiferromagnet BaCo2V2O8
We report a neutron diffraction and muon spin relaxation muSR study of static
and dynamical magnetic properties of BaCo2V2O8, a quasi-one-dimensional
spin-chain system. A proposed model for the antiferromagnetic structure
includes: a propagation vector k_AF = (0, 0, 1), independent of external
magnetic fields for fields below a critical value H_c(T). The ordered moments,
of 2.18 \mu_B per Co ion, are aligned along the crystallographic c-axis. Within
the screw chains, along the c axis, the moments are arranged
antiferromagnetically. In the basal planes the spins are arranged
ferromagnetically (forming zig-zags paths) along one of the axis and
antiferromagnetically along the other. The temperature dependence of the
sub-lattice magnetization is consistent with the expectations of the 3D Ising
model. A similar behavior is observed for the internal static fields at
different muon stopping sites. Muon time spectra measured at weak longitudinal
fields and temperatures much higher than T_N can be well described using a
single muon site with an exponential muon spin relaxation that gradually
changes into an stretched exponential on approaching T_N. The
temperature-induced changes of the relaxation suggest that the Co fluctuations
dramatically slow down and the system becomes less homogeneous as it approaches
the antiferromagnetic state.Comment: 7 pages, 9 figure
Stability of critical bubble in stretched fluid of square-gradient density-functional model with triple-parabolic free energy
The square-gradient density-functional model with triple-parabolic free
energy, that was used previously to study the homogeneous bubble nucleation [J.
Chem. Phys. 129, 104508 (2008)], is used to study the stability of the critical
bubble nucleated within the bulk under-saturated stretched fluid. The stability
of the bubble is studied by solving the Schr\"odinger equation for the
fluctuation. The negative eigenvalue corresponds to the unstable growing mode
of the fluctuation. Our results show that there is only one negative eigenvalue
whose eigenfunction represents the fluctuation that corresponds to the
isotropically growing or shrinking nucleus. In particular, this negative
eigenvalue survives up to the spinodal point. Therefore the critical bubble is
not fractal or ramified near the spinodal.Comment: 9 pages, 8 figures, Journal of Chemical Physics accepted for
publicatio
- …