21,320 research outputs found
A remark on zeta functions of finite graphs via quantum walks
From the viewpoint of quantum walks, the Ihara zeta function of a finite
graph can be said to be closely related to its evolution matrix. In this note
we introduce another kind of zeta function of a graph, which is closely related
to, as to say, the square of the evolution matrix of a quantum walk. Then we
give to such a function two types of determinant expressions and derive from it
some geometric properties of a finite graph. As an application, we illustrate
the distribution of poles of this function comparing with those of the usual
Ihara zeta function.Comment: 14 pages, 1 figur
Phytohaemagglutinin on maternal and umbilical leukocytes
Almost all the umbilical lymphocytes showed more extensive blast cell formation
than that of their mother's lymphocytes with PHA. Pathological conditions of mother in pregnancy and labor such as anemia, gestational toxicosis,
difficult labor and asphyxia of babies, inhibited the normal response of both maternal and umbilical lymphocytes to PHA.</p
Nodal Structure of Superconductors with Time-Reversal Invariance and Z2 Topological Number
A topological argument is presented for nodal structures of superconducting
states with time-reversal invariance. A generic Hamiltonian which describes a
quasiparticle in superconducting states with time-reversal invariance is
derived, and it is shown that only line nodes are topologically stable in
single-band descriptions of superconductivity. Using the time-reversal
symmetry, we introduce a real structure and define topological numbers of line
nodes. Stability of line nodes is ensured by conservation of the topological
numbers. Line nodes in high-Tc materials, the polar state in p-wave paring and
mixed singlet-triplet superconducting states are examined in detail.Comment: 11 pages, 8 figure
Enhancement of polarization in a spin-orbit coupling quantum wire with a constriction
We investigate the enhancement of spin polarization in a quantum wire in the
presence of a constriction and a spin-orbit coupling segment. It is shown that
the spin-filtering effect is significantly heightened in comparison with the
configuration without the constriction. It is understood in the studies that
the constriction structure plays a critical role in enhancing the spin
filtering by means of confining the incident electrons to occupy one channel
only while the outgoing electrons occupy two channels. The enhancement of
spin-filtering has also been analyzed within the perturbation theory. Because
the spin polarization arises mainly from the scattering between the
constriction and the segment with spin-orbit coupling, the sub-band mixing
induced by spin-orbit interaction in the scattering process and the
interferences result in higher spin-filtering effect.Comment: 8 pages, 7 figure
Robust strongly-modulated transmission of a -shaped structure with local Rashba interaction
We propose a scheme of spin transistor using a -shaped structure with
local Rashba interaction. A wide antiresonance energy gap appears due to the
interplay of two types of interference, the Fano-Rashba interference and the
structure interference. A large current from the gap area can be obtained via
changing the Rashba strength and/or the length of the sidearm by using gate
voltage. The robustness of the antiresonance gap against strong disorder is
demonstrated and shows the feasibility of this structure for the real
application.Comment: 4 pages, 3 figures, To be published in PR
Non Abelian Sugawara Construction and the q-deformed N=2 Superconformal Algebra
The construction of a q-deformed N=2 superconformal algebra is proposed in
terms of level 1 currents of quantum affine
Lie algebra and a single real Fermi field. In particular, it suggests the
expression for the q-deformed Energy-Momentum tensor in the Sugawara form. Its
constituents generate two isomorphic quadratic algebraic structures. The
generalization to is also proposed.Comment: AMSLATEX, 21page
Spacetime Superalgebra in AdS_4 \times S^7 via Supermembrane Probe
The spacetime superalgebra via the supermembrane probe in the background of
AdS_4 \times S^7 is discussed to the lowest order in the spinor coordinate
\t. To obtain the correct spacetime superalgebras, all \t^2 order
corrections for supervielbein and super 3-form gauge potential have to be
included. The central extension of the superalgebra OSp(8|4) of the super
isometries for AdS_4 \times S^7 is found.Comment: 8 pages, Latex, minor corrections, final version to appear in Phys.
Rev.
A Symmetric Generalization of Linear B\"acklund Transformation associated with the Hirota Bilinear Difference Equation
The Hirota bilinear difference equation is generalized to discrete space of
arbitrary dimension. Solutions to the nonlinear difference equations can be
obtained via B\"acklund transformation of the corresponding linear problems.Comment: Latex, 12 pages, 1 figur
Anisotropic magnetic fluctuations in the ferromagnetic superconductor UCoGe studied by angle-resolved ^{59}Co NMR
We have carried out direction-dependent ^{59}Co NMR experiments on a single
crystal sample of the ferromagnetic superconductor UCoGe in order to study the
magnetic properties in the normal state. The Knight shift and nuclear
spin-lattice relaxation rate measurements provide microscopic evidence that
both static and dynamic susceptibilities are ferromagnetic with strong Ising
anisotropy. We discuss that superconductivity induced by these magnetic
fluctuations prefers spin-triplet pairing state.Comment: 4 pages, 4 figure
Multivariate Bernoulli and Euler polynomials via L\'evy processes
By a symbolic method, we introduce multivariate Bernoulli and Euler
polynomials as powers of polynomials whose coefficients involve multivariate
L\'evy processes. Many properties of these polynomials are stated
straightforwardly thanks to this representation, which could be easily
implemented in any symbolic manipulation system. A very simple relation between
these two families of multivariate polynomials is provided
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