1,414,984 research outputs found
Joint Formation of QSOs and Spheroids: QSOs as clocks of star formation in Spheroids
Direct and indirect observational evidence leads to the conclusion that high
redshift QSOs did shine in the core of early type proto-galaxies during their
main episode of star formation. Exploting this fact, we derive the rate of
formation of this kind of stellar systems at high redshift by using the QSO
Luminosity Function. The elemental proportions in elliptical galaxies, the
descendents of the QSO hosts, suggest that the star formation was more rapid in
more massive objects. We show that this is expected to occur in Dark Matter
haloes, when the processes of cooling and heating is considered. This is also
confirmed by comparing the observed sub-mm counts to those derived by coupling
the formation rate and the star formation rate of the spheroidal galaxies with
a detailed model for their SED evolution. In this scenario SCUBA galaxies and
Lyman Break Galaxies are early type proto-galaxies forming the bulk of their
stars before the onset of QSO activity.Comment: 13 pages, 8 figures, accepted by MNRAS, major revision of the
formalis
Localization and superconducting proximity effect in sandwiched potassium films
Thin films of alkali metals when sandwiched at both surfaces by thin metal
films loose their conductance. The superconducting proximity effect is used to
investigate the change in the alkali film. On the length scale of the film
thickness the electronic properties of the alkali film do not change noticeably
although its conductance is dramatically reduced, corresponding to localized
electrons.Comment: 13 pages, 5 figure
Probability tables
The idea of writing a table of probabilistic data for a quantum or classical
system, and of decomposing this table in a compact way, leads to a shortcut for
Hardy's formalism, and gives new perspectives on foundational issues.Comment: LaTeX, 17 pages, 1 figure. Contribution to the conference ``Quantum
Theory: Reconsideration of Foundations 2'' (Vaexjoe, Sweden, 2003). To appear
in the Proceedings (the notation in this version has been slightly modified,
and the references updated
Motion of vortices in type II superconductors
The methods of formal asymptotics are used to examine the behaviour of a system of curvilinear vortices in a type II superconductor as the thickness of the vortex cores tends to zero. The vortices then appear as singularities in the field equation and are analagous to line vortices in inviscid hydrodynamics. A local analysis near each vortex core gives an equation of motion governing the evolution of these singularities
Entanglement renormalization
In the context of real-space renormalization group methods, we propose a
novel scheme for quantum systems defined on a D-dimensional lattice. It is
based on a coarse-graining transformation that attempts to reduce the amount of
entanglement of a block of lattice sites before truncating its Hilbert space.
Numerical simulations involving the ground state of a 1D system at criticality
show that the resulting coarse-grained site requires a Hilbert space dimension
that does not grow with successive rescaling transformations. As a result we
can address, in a quasi-exact way, tens of thousands of quantum spins with a
computational effort that scales logarithmically in the system's size. The
calculations unveil that ground state entanglement in extended quantum systems
is organized in layers corresponding to different length scales. At a quantum
critical point, each rellevant length scale makes an equivalent contribution to
the entanglement of a block with the rest of the system.Comment: 4 pages, 4 figures, updated versio
Grover Algorithm with zero theoretical failure rate
In standard Grover's algorithm for quantum searching, the probability of
finding the marked item is not exactly 1. In this Letter we present a modified
version of Grover's algorithm that searches a marked state with full successful
rate. The modification is done by replacing the phase inversion by two phase
rotation through angle . The rotation angle is given analytically to be
, where
, the number of items in the database, and
an integer equal to or greater than the integer part of . Upon measurement at -th iteration, the marked state
is obtained with certainty.Comment: 5 pages. Accepted for publication in Physical Review
Solitary wave complexes in two-component mixture condensates
Axisymmetric three-dimensional solitary waves in uniform two-component
mixture Bose-Einstein condensates are obtained as solutions of the coupled
Gross-Pitaevskii equations with equal intracomponent but varying intercomponent
interaction strengths. Several families of solitary wave complexes are found:
(1) vortex rings of various radii in each of the components, (2) a vortex ring
in one component coupled to a rarefaction solitary wave of the other component,
(3) two coupled rarefaction waves, (4) either a vortex ring or a rarefaction
pulse coupled to a localised disturbance of a very low momentum. The continuous
families of such waves are shown in the momentum-energy plane for various
values of the interaction strengths and the relative differences between the
chemical potentials of two components. Solitary wave formation, their stability
and solitary wave complexes in two-dimensions are discussed.Comment: 4 pages, 2 figures, 2 table
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