7,661 research outputs found
Strings of droplets propelled by coherent waves
Bouncing walking droplets possess fascinating properties due to their
peculiar wave/particule interaction. In order to study such walkers in a 1d
system, we considered the case of one or more droplets in an annular cavity. We
show that, in this geometry, walking droplets form a string of synchronized
bouncing droplets that share a common coherent wave propelling the group at a
speed faster than single walkers. The formation of this coherent wave and the
collective behavior of droplets is captured by a model.Comment: 5 Pages, 5 Figures, 2 supplementary movies (identical), supplementary
.pdf fil
Credit exclusion in quantitative models of bankruptcy: does it matter?
Bankruptcy ; Credit
Magnetic domain formation in itinerant metamagnets
We examine the effects of long-range dipolar forces on metamagnetic
transitions and generalize the theory of Condon domains to the case of an
itinerant electron system undergoing a first-order metamagnetic transition. We
demonstrate that within a finite range of the applied field, dipolar
interactions induce a spatial modulation of the magnetization in the form of
stripes or bubbles. Our findings are consistent with recent observations in the
bilayer ruthenate SrRuO.Comment: 4 pages, 3 figures, minor changes, references adde
Effects of crucible wetting during solidification of immiscible Pb-Zn
Many industrial uses for liquid phase miscibility gap alloys are proposed. However, the commercial production of these alloys into useful ingots with a reasonable amount of homogeneity is arduous because of their immiscibility in the liquid state. In the low-g environment of space gravitational settling forces are abated, thus solidification of an immiscible alloys with a uniform distribution of phases becomes feasible. Elimination of gravitational settling and coalescence processes in low-g also makes possible the study of other separation and coarsening mechanisms. Even with gravitational separation forces reduced, many low-g experiments have resulted in severely segregated structures. The segregation in many cases was due to preferential wetting of the crucible by one of the immiscible liquids. The objective was to analyze the wetting behavior of Pb-Zn alloys on various crucible materials in an effort to identify a crucible in which the fluid flow induced by preferential wetting is minimized. It is proposed that by choosing the crucible for a particular alloy so that the difference in surface energy between the solid and two liqud phases is minimized, the effects of preferential wetting can be diminished and possibly avoided. Qualitative experiments were conducted and have shown the competitive wetting behavior of the immiscible Pb-Zn system and 13 different crucible materials
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The SLIM (Social learning for the integrated management and sustainable use of water at catchment scale) Final Report
Background: SLIM stands for 'Socuak Learning for the Integrated Management and Sustainable Use of Water at Catchment Scale'. It is a multi-country research project funded by the European Commission (DG RESEARCH - 5th Framework Programme for research and technological development, 1998-2002). Its main theme is the investigation of the socio-economic aspects of the sustainable use of water. Within this theme, its main focus of interest lies in understanding the application of social learning as a conceptual framework, an operational principle, a policy instrument and a process of systemic change
Inequivalent classes of closed three-level systems
We show here that the and V configurations of three-level atomic
systems, while they have recently been shown to be equivalent for many
important physical quantities when driven with classical fields [M. B. Plenio,
Phys. Rev. A \textbf{62}, 015802 (2000)], are no longer equivalent when coupled
via a quantum field. We analyze the physical origin of such behavior and show
how the equivalence between these two configurations emerges in the
semiclassical limit.Comment: 4 pages, 1 figure. To appear as Brief Report in Physical Review
Entanglement Entropy in the Two-Dimensional Random Transverse Field Ising Model
The scaling behavior of the entanglement entropy in the two-dimensional
random transverse field Ising model is studied numerically through the strong
disordered renormalization group method. We find that the leading term of the
entanglement entropy always scales linearly with the block size. However,
besides this \emph{area law} contribution, we find a subleading logarithmic
correction at the quantum critical point. This correction is discussed from the
point of view of an underlying percolation transition, both at finite and at
zero temperature.Comment: 4.3 pages, 4 figure
Discrete phase-space approach to mutually orthogonal Latin squares
We show there is a natural connection between Latin squares and commutative
sets of monomials defining geometric structures in finite phase-space of prime
power dimensions. A complete set of such monomials defines a mutually unbiased
basis (MUB) and may be associated with a complete set of mutually orthogonal
Latin squares (MOLS). We translate some possible operations on the monomial
sets into isomorphisms of Latin squares, and find a general form of
permutations that map between Latin squares corresponding to unitarily
equivalent mutually unbiased sets. We extend this result to a conjecture: MOLS
associated to unitarily equivalent MUBs will always be isomorphic, and MOLS
associated to unitarily inequivalent MUBs will be non-isomorphic
Raman transitions between hyperfine clock states in a magnetic trap
We present our experimental investigation of an optical Raman transition
between the magnetic clock states of Rb in an atom chip magnetic trap.
The transfer of atomic population is induced by a pair of diode lasers which
couple the two clock states off-resonantly to an intermediate state manifold.
This transition is subject to destructive interference of two excitation paths,
which leads to a reduction of the effective two-photon Rabi-frequency.
Furthermore, we find that the transition frequency is highly sensitive to the
intensity ratio of the diode lasers. Our results are well described in terms of
light shifts in the multi-level structure of Rb. The differential light
shifts vanish at an optimal intensity ratio, which we observe as a narrowing of
the transition linewidth. We also observe the temporal dynamics of the
population transfer and find good agreement with a model based on the system's
master equation and a Gaussian laser beam profile. Finally, we identify several
sources of decoherence in our system, and discuss possible improvements.Comment: 10 pages, 7 figure
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