6,826 research outputs found
Guaranteed emergence of genuine entanglement in 3-qubit evolving systems
Multipartite entanglement has been shown to be of particular relevance for a
better understanding and exploitation of the dynamics and flow of entanglement
in multiparty systems. This calls for analysis aimed at identifying the
appropriate processes that guarantee the emergence of multipartite entanglement
in a wide range of scenarios. Here we carry on such analysis considering a
system of two initially entangled qubits, one of which is let to interact with
a third qubit according to an arbitrary unitary evolution. We establish
necessary and sufficient conditions on the corresponding Kraus operators, to
discern whether the evolved state pertains to either one of the classes of
3-qubit pure states that exhibit some kind of entanglement, namely biseparable,
W-, and GHZ- genuine entangled classes. Our results provide a classification of
the Kraus operators according to their capacity of producing 3-qubit
entanglement, and pave the way for extending the analysis to larger systems and
determining the particular interactions that must be implemented in order to
create, enhance and distribute entanglement in a specific manner.Comment: Two new subsections included. Accepted for publication in The
European Physical Journal
Reciprocity of Networks with Degree Correlations and Arbitrary Degree Sequences
Although most of the real networks contain a mixture of directed and
bidirectional (reciprocal) connections, the reciprocity has received little
attention as a subject of theoretical understanding. We study the expected
reciprocity of networks with an arbitrary degree sequence and a broad class of
degree correlations by means of statistical ensemble approach. We demonstrate
that degree correlations are crucial to understand the reciprocity in real
networks and a hierarchy of correlation contributions to is revealed.
Numerical experiments using novel network randomization methods show very good
agreement to our analytical estimations.Comment: 8 pages, 3 figures, added a new table and a new figure, accepted for
publication in Phys.Rev.
Probing the Majorana neutrinos and their CP violation in decays of charged scalar mesons
Some of the outstanding questions of particle physics today concern the
neutrino sector, in particular whether there are more neutrinos than those
already known and whether they are Dirac or Majorana particles.There are
different ways to explore these issues. In this article we describe
neutrino-mediated decays of charged pseudoscalar mesons such as ,
and , in scenarios where extra neutrinos are heavy and can
be on their mass shell. We discuss semileptonic and leptonic decays of such
kinds. We investigate possible ways of using these decays in order to
distinguish between the Dirac and Majorana character of neutrinos. Further, we
argue that there are significant possibilities of detecting CP violation in
such decays when there are at least two almost degenerate Majorana neutrinos
involved. This latter type of scenario fits well into the known neutrino
minimal standard model (MSM) which could simultaneously explain the Dark
Matter and Baryon Asymmetry of the Universe.Comment: v3: 37 pages, 14 figures; minor typographical errors corrected;
published in Symmetr
Characterization of digital dispersive spectrometers by low coherence interferometry
We propose a procedure to determine the spectral response of digital dispersive spectrometers without previous knowledge of any parameter of the system. The method consists of applying the Fourier transform spectroscopy technique to each pixel of the detection plane, a CCD camera, to obtain its individual spectral response. From this simple procedure, the system-point spread function and the effect of the finite pixel width are taken into account giving rise to a response matrix that fully characterizes the spectrometer. Using the response matrix information we find the resolving power of a given spectrometer, predict in advance its response to any virtual input spectrum and improve numerically the spectrometer's resolution. We consider that the presented approach could be useful in most spectroscopic branches such as in computational spectroscopy, optical coherence tomography, hyperspectral imaging, spectral interferometry and analytical chemistry, among others.Fil: Martínez Matos, Ó.. Universidad Complutense de Madrid; EspañaFil: Rickenstorff, C.. Universidad Complutense de Madrid; EspañaFil: Zamora, S.. Universidad Complutense de Madrid; EspañaFil: Izquierdo, J. G.. Universidad Complutense de Madrid; EspañaFil: Vaveliuk, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentin
Thin Film Formation During Splashing of Viscous Liquids
After impact onto a smooth dry surface, a drop of viscous liquid initially
spreads in the form of a thick lamella. If the drop splashes, it first emits a
thin fluid sheet that can ultimately break up into droplets causing the splash.
Ambient gas is crucial for creating this thin sheet. The time for sheet
ejection, , depends on impact velocity, liquid viscosity, gas pressure
and molecular weight. A central air bubble is trapped below the drop at
pressures even below that necessary for this sheet formation. In addition, air
bubbles are entrained underneath the spreading lamella when the ejected sheet
is present. Air entrainment ceases at a lamella velocity that is independent of
drop impact velocity as well as ambient gas pressure.Comment: 8 pages, 11 figure
Vortices on demand in multicomponent Bose-Einstein condensates
We present a simple mechanism to produce vortices at any desired spatial
locations in harmonically trapped Bose-Einstein condensates (BEC) with
multicomponent spin states coupled to external transverse and axial magnetic
fields. The vortices appear at the spatial points where the spin-transverse
field interaction vanishes and, depending on the multipolar magnetic field
order, the vortices can acquire different predictable topological charges. We
explicitly demonstrate our findings, both numerically and analytically, by
analyzing a 2D BEC via the Gross-Pitaevskii equation for atomic systems with
either two or three internal states. We further show that, by an spontaneous
symmetry breaking mechanism, vortices can appear in any spin component, unless
symmetry is externally broken at the outset by an axial field. We suggest that
this scenario may be tested using an ultracold gas of Rb occupying all
three states in an optical trap.Comment: 11 pages, 9 figures, (Accepted in PRA
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