11,263 research outputs found
Practical dispersion relations for strongly coupled plasma fluids
Very simple explicit analytical expressions are discussed, which are able to
describe the dispersion relations of longitudinal waves in strongly coupled
plasma systems such as one-component plasma and weakly screened Yukawa fluids
with a very good accuracy. Applications to other systems with soft pairwise
interactions are briefly discussed.Comment: 11 pages, 3 figures; Related to arXiv:1711.0615
Statistical Description of Hydrodynamic Processes in Ionic Melts with taking into account Polarization Effects
Statistical description of hydrodynamic processes for ionic melts is proposed
with taking into account polarization effects caused by the deformation of
external ionic shells. This description is carried out by means of the Zubarev
nonequilibrium statistical operator method, appropriate for investigations of
both strong and weak nonequilibrium processes. The nonequilibrium statistical
operator and the generalized hydrodynamic equations that take into account
polarization processes are received for ionic-polarization model of ionic
molten salts when the nonequilibrium averaged values of densities of ions
number, their momentum, dipole momentum and total energy are chosen for the
reduced description parameters. A spectrum of collective excitations is
investigated within the viscoelastic approximation for ion-polarization model
of ionic melts.Comment: 24 pages, RevTex4.1-format, no figure
Dynamical Realization of Macroscopic Superposition States of Cold Bosons in a Tilted Double Well
We present exact expressions for the quantum sloshing of Bose-Einstein
condensates in a tilted two-well potential. Tunneling is suppressed by a small
potential difference between wells, or tilt. However, tunneling resonances
occur for critical values of the tilt when the barrier is high. At resonance,
tunneling times on the order of 10-100 ms are possible. Furthermore, such
tilted resonances lead to a dynamical scheme for creating few-body NOON-like
macroscopic superposition states which are protected by the many body
wavefunction against potential fluctuations.Comment: 6 pages, 5 figures, final version, only minor changes from previous
arXiv versio
Pressure-induced phase transitions and high-pressure tetragonal phase of Fe1.08Te
We report the effects of hydrostatic pressure on the temperature-induced
phase transitions in Fe1.08Te in the pressure range 0-3 GPa using synchrotron
powder x-ray diffraction (XRD). The results reveal a plethora of phase
transitions. At ambient pressure, Fe1.08Te undergoes simultaneous first-order
structural symmetry-breaking and magnetic phase transitions, namely from the
paramagnetic tetragonal (P4/nmm) to the antiferromagnetic monoclinic (P2_1/m)
phase. We show that, at a pressure of 1.33 GPa, the low temperature structure
adopts an orthorhombic symmetry. More importantly, for pressures of 2.29 GPa
and higher, a symmetry-conserving tetragonal-tetragonal phase transition has
been identified from a change in the c/a ratio of the lattice parameters. The
succession of different pressure and temperature-induced structural and
magnetic phases indicates the presence of strong magneto-elastic coupling
effects in this material.Comment: 11 page
Phase transitions near black hole horizons
The Reissner-Nordstrom black hole in four dimensions can be made unstable
without violating the dominant energy condition by introducing a real massive
scalar with non-renormalizable interactions with the gauge field. New stable
black hole solutions then exist with greater entropy for fixed mass and charge
than the Reissner-Nordstrom solution. In these new solutions, the scalar
condenses to a non-zero value near the horizon. Various generalizations of
these hairy black holes are discussed, and an attempt is made to characterize
when black hole hair can occur.Comment: 30 pages, 6 figures. v2: minor corrections, references adde
A Three Dimensional Lattice of Ion Traps
We propose an ion trap configuration such that individual traps can be
stacked together in a three dimensional simple cubic arrangement. The isolated
trap as well as the extended array of ion traps are characterized for different
locations in the lattice, illustrating the robustness of the lattice of traps
concept. Ease in the addressing of ions at each lattice site, individually or
simultaneously, makes this system naturally suitable for a number of
experiments. Application of this trap to precision spectroscopy, quantum
information processing and the study of few particle interacting system are
discussed.Comment: 4 pages, 4 Figures. Fig 1 appears as a composite of 1a, 1b, 1c and
1d. Fig 2 appears as a composite of 2a, 2b and 2
Two-particle photoemission from strongly correlated systems: A dynamical-mean field approach
We study theoretically the simultaneous, photo-induced two-particle
excitations of strongly correlated systems on the basis of the Hubbard model.
Under certain conditions specified in this work, the corre- sponding transition
probability is related to the two-particle spectral function which we calculate
using three different methods: the dynamical-mean field theory combined with
quantum Monte Carlo (DMFT- QMC) technique, the first order perturbation theory
and the ladder approximations. The results are analyzed and compared for
systems at the verge of the metal-insulator transitions. The dependencies on
the electronic correlation strength and on doping are explored. In addition,
the account for the orbital degeneracy allows an insight into the influence of
interband correlations on the two particle excitations. A suitable experimental
realization is discussed.Comment: 25 pp, 10 figs. to be published in PR
Magnetic order in GdBiPt studied by x-ray resonant magnetic scattering
Rare earth (R) half-Heusler compounds, RBiPt, exhibit a wide spectrum of
novel ground states. Recently, GdBiPt has been proposed as a potential
antiferromagnetic topological insulator (AFTI). We have employed x-ray resonant
magnetic scattering to elucidate the microscopic details of the magnetic
structure in GdBiPt below T_N = 8.5 K. Experiments at the Gd L_2 absorption
edge show that the Gd moments order in an antiferromagnetic stacking along the
cubic diagonal [1 1 1] direction satisfying the requirement for an AFTI, where
both time-reversal symmetry and lattice translational symmetry are broken, but
their product is conserved.Comment: 4 pages, 4 figure
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