139,390 research outputs found
Noncommutative tori and universal sets of non-binary quantum gates
A problem of universality in simulation of evolution of quantum system and in
theory of quantum computations is related with the possibility of expression or
approximation of arbitrary unitary transformation by composition of specific
unitary transformations (quantum gates) from given set. In an earlier paper
(quant-ph/0010071) application of Clifford algebras to constructions of
universal sets of binary quantum gates was shown. For
application of a similar approach to non-binary quantum gates
in present work is used rational noncommutative torus . A
set of universal non-binary two-gates is presented here as one example.Comment: 5 pages, REVTeX3.1, v2: spelling and misprints, 4 new ref
ASDTIC control and standardized interface circuits applied to buck, parallel and buck-boost dc to dc power converters
Versatile standardized pulse modulation nondissipatively regulated control signal processing circuits were applied to three most commonly used dc to dc power converter configurations: (1) the series switching buck-regulator, (2) the pulse modulated parallel inverter, and (3) the buck-boost converter. The unique control concept and the commonality of control functions for all switching regulators have resulted in improved static and dynamic performance and control circuit standardization. New power-circuit technology was also applied to enhance reliability and to achieve optimum weight and efficiency
The application of the analog signal to discrete time interval converter to the signal conditioner power supplies
The Analog Signal to Discrete Time Interval Converter microminiaturized module was utilized to control the signal conditioner power supplies. The multi-loop control provides outstanding static and dynamic performance characteristics, exceeding those generally associated with single-loop regulators. Eight converter boards, each containing three independent dc to dc converter, were built, tested, and delivered
Nonmonotonic temperature dependence of critical current in diffusive d-wave junctions
We study the Josephson effect in D/I/DN/I/D junctions, where I, DN and D
denote an insulator, a diffusive normal metal and a d-wave superconductor,
respectively.The Josephson current is calculated based on the quasiclassical
Green's function theory with a general boundary condition for unconventional
superconducting junctions. In contrast to s-wave junctions, the product of the
Josephson current and the normal state resistance is enhanced by making the
interface barriers stronger. The Josephson current has a nonmonotonic
temperature dependence due to the competition between the proximity effect and
the midgap Andreev resonant states.Comment: 5 pages, 4 figure
Comments on Worldsheet Description of the Omega Background
Nekrasov's partition function is defined on a flat bundle of R^4 over S^1
called the Omega background. When the fibration is self-dual, the partition
function is known to be equal to the topological string partition function,
which computes scattering amplitudes of self-dual gravitons and graviphotons in
type II superstring compactified on a Calabi-Yau manifold. We propose a
generalization of this correspondence when the fibration is not necessarily
self-dual.Comment: 11 page
Motion of a condensate in a shaken and vibrating harmonic trap
The dynamics of a Bose-Einstein condensate (BEC) in a time-dependent harmonic
trapping potential is determined for arbitrary variations of the position of
the center of the trap and its frequencies. The dynamics of the BEC wavepacket
is soliton-like. The motion of the center of the wavepacket, and the spatially
and temporally dependent phase (which affects the coherence properties of the
BEC) multiplying the soliton-like part of the wavepacket, are analytically
determined.Comment: Accepted for publication in J. Phys. B: At Mol Opt Phy
Dynamical origin and the pole structure of X(3872)
The dynamical mechanism of channel coupling with the decay channels is
applied to the case of coupled charmonium - states with .
A pole analysis is done and the production cross section is calculated
in qualitative agreement with experiment. The sharp peak at the
threshold and flat background are shown to be due to Breit-Wigner resonance,
shifted by channel coupling from the original position of 3954 MeV for the
, state. A similar analysis, applied to the , ,
, , allows us to associate the first one with the observed
J=2 and explains the destiny of .Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev. Let
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