525 research outputs found
Kahler-Einstein metrics on log del Pezzo surfaces in weighted projective 3-spaces
We determine the complete list of anticanonically embedded quasi smooth log
del Pezzo surfaces in weighted projective 3-spaces. We prove that many of these
admit a K\"ahler-Einstein metric and most of them do not have tigers.Comment: 10 pages, LaTe
Measurement of Light Intensity Based on a Flip-flop Sensor
This paper deals with a new type of system for measuring light intensity with the use of a flip-flop sensor controlled by a so-called slow-rise voltage control pulse. A photodiode was used for quantification of the measured light intensity in the structure of the flip-flop. The theoretical considerations are compared with experimental results, and good agreement is reported
Directional correlations in quantum walks with two particles
Quantum walks on a line with a single particle possess a classical analogue. Involving more walkers opens up the possibility of studying collective quantum effects, such as many-particle correlations. In this context, entangled initial states and the indistinguishability of the particles play a role. We consider the directional correlations between two particles performing a quantum walk on a line. For non-interacting particles, we find analytic asymptotic expressions and give the limits of directional correlations. We show that by introducing delta-interaction between the particles, one can exceed the limits for non-interacting particles
Numerical modelling of electric conductance of a thin sheet
In this paper the numeric modelling of total resistance of a thin sheet, with local conductivity in randomly
distributed grains higher then is that of the basic matrix, is presented. The 2D model is formed by a structure of longitudinal
and transversal conductors interconnected in nodes of a square net. In all nodes, using iteration procedure, the potential is
determined from which the conductance of sheet is computed between two touching electrodes. The described model can be
used to imitate the behaviour of heterogeneous thin conducting sheets prepared by different techniques. The model was
verified in some cases where the net resistance is well known from the theory
Full-revivals in 2-D Quantum Walks
Recurrence of a random walk is described by the Polya number. For quantum
walks, recurrence is understood as the return of the walker to the origin,
rather than the full-revival of its quantum state. Localization for two
dimensional quantum walks is known to exist in the sense of non-vanishing
probability distribution in the asymptotic limit. We show on the example of the
2-D Grover walk that one can exploit the effect of localization to construct
stationary solutions. Moreover, we find full-revivals of a quantum state with a
period of two steps. We prove that there cannot be longer cycles for a
four-state quantum walk. Stationary states and revivals result from
interference which has no counterpart in classical random walks
The cone of curves of Fano varieties of coindex four
We classify the cones of curves of Fano varieties of dimension greater or
equal than five and (pseudo)index dim X -3, describing the number and type of
their extremal rays.Comment: 27 pages; changed the numbering of Theorems, Definitions,
Propositions, etc. in accordance with the published version to avoid
incorrect reference
Log Fano varieties over function fields of curves
Consider a smooth log Fano variety over the function field of a curve.
Suppose that the boundary has positive normal bundle. Choose an integral model
over the curve. Then integral points are Zariski dense, after removing an
explicit finite set of points on the base curve.Comment: 18 page
Diffeomorphisms and families of Fourier-Mukai transforms in mirror symmetry
Assuming the standard framework of mirror symmetry, a conjecture is
formulated describing how the diffeomorphism group of a Calabi-Yau manifold Y
should act by families of Fourier-Mukai transforms over the complex moduli
space of the mirror X. The conjecture generalizes a proposal of Kontsevich
relating monodromy transformations and self-equivalences. Supporting evidence
is given in the case of elliptic curves, lattice-polarized K3 surfaces and
Calabi-Yau threefolds. A relation to the global Torelli problem is discussed.Comment: Approx. 20 pages LaTeX. One reference adde
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