19,656 research outputs found
Area/latency optimized early output asynchronous full adders and relative-timed ripple carry adders
This article presents two area/latency optimized gate level asynchronous full
adder designs which correspond to early output logic. The proposed full adders
are constructed using the delay-insensitive dual-rail code and adhere to the
four-phase return-to-zero handshaking. For an asynchronous ripple carry adder
(RCA) constructed using the proposed early output full adders, the
relative-timing assumption becomes necessary and the inherent advantages of the
relative-timed RCA are: (1) computation with valid inputs, i.e., forward
latency is data-dependent, and (2) computation with spacer inputs involves a
bare minimum constant reverse latency of just one full adder delay, thus
resulting in the optimal cycle time. With respect to different 32-bit RCA
implementations, and in comparison with the optimized strong-indication,
weak-indication, and early output full adder designs, one of the proposed early
output full adders achieves respective reductions in latency by 67.8, 12.3 and
6.1 %, while the other proposed early output full adder achieves corresponding
reductions in area by 32.6, 24.6 and 6.9 %, with practically no power penalty.
Further, the proposed early output full adders based asynchronous RCAs enable
minimum reductions in cycle time by 83.4, 15, and 8.8 % when considering
carry-propagation over the entire RCA width of 32-bits, and maximum reductions
in cycle time by 97.5, 27.4, and 22.4 % for the consideration of a typical
carry chain length of 4 full adder stages, when compared to the least of the
cycle time estimates of various strong-indication, weak-indication, and early
output asynchronous RCAs of similar size. All the asynchronous full adders and
RCAs were realized using standard cells in a semi-custom design fashion based
on a 32/28 nm CMOS process technology
Quantum interference due to crossed Andreev reflection in a d-wave superconductor with two nano-contacts
The crossed Andreev reflection in a hybrid nanostructure consisting of a
d-wave superconductor and two quantum wires is theoretically studied. When the
(110) oriented surface of the superconductor is in contact with the wires
parallel and placed close to each other, the Andreev bound state is formed by
the crossed Andreev reflection. The conductance has two resonance peaks well
below the gap structure in the case of tunnel contacts. These peaks originate
from the bonding and antibonding Andreev bound states of hole wave functions.Comment: 4 pages, 3 figure
Supersymmetric Heavy Higgses at e^+e^- Linear Collider and Dark-Matter Physics
We consider the capability of the e^+e^- linear collider (which is recently
called as the International Linear Collider, or ILC) for studying the
properties of the heavy Higgs bosons in the supersymmetric standard model. We
pay special attention to the large \tan\beta region which is motivated, in
particular, by explaining the dark-matter density of the universe (i.e.,
so-called ``rapid-annihilation funnels''). We perform a systematic analysis to
estimate expected uncertainties in the masses and widths of the heavy Higgs
bosons assuming an energy and integrated luminosity of \sqrt{s}=1 TeV and L=1
ab^{-1}. We also discuss its implication to the reconstruction of the
dark-matter density of the universe.Comment: 28 pages, 13 figures, version to appear in PR
Joule heating generated by spin current through Josephson junctions
We theoretically study the spin-polarized current flowing through a Josephson
junction (JJ) in a spin injection device. When the spin-polarized current is
injected from a ferromagnet (FM) in a superconductor (SC), the charge current
is carried by the superconducting condensate (Cooper pairs), while the spin-up
and spin-down currents flow in the equal magnitude but in the opposite
direction in SC, because of no quasiparticle charge current in SC. This
indicates that not only the Josephson current but also the spin current flow
across JJ at zero bias voltage, thereby generating Joule heating by the spin
current. The result provides a new method for detecting the spin current by
measuring Joule heating at JJ.Comment: 3 pages, 2 figure
The Hosotani Mechanism in Bulk Gauge Theories with an Orbifold Extra Space S^1/Z_2
We pursue the possibility of the scenario in which the Higgs field is
identified with the extra-space component of a bulk gauge field. The space-time
we take is M S/Z. We show that a non-trivial
Z-parity assignment allows some of the extra-space component to have
radiatively induced VEV, which strongly modifies the mass spectrum and gauge
symmetry of the theory, realized by oribifolding. In particular we investigate
the dynamical mass generation of zero-mode fermion and spontaneous gauge
symmetry breaking due to the VEV. The gauge theories we adopt are a prototype
model SU(2) and SU(3) model, of special interest as the realistic minimal
scheme to incorporate the standard model SU(2) U(1).Comment: 16 pages 3 figure
Structure of super-families
At present the study of nuclear interactions induced by cosmic rays is the unique source of information on the nuclear interactions in the energy region above 10 to the 15th power eV. The phenomena in this energy region are observed by air shower arrays or emulsion chambers installed at high mountain. An emulsion chamber is the pile of lead plates and photo-sensitive layers (nuclear emulsion plates and/or X-ray films) used to detect electron showers. High spatial resolution of photographic material used in the emulsion chamber enables the observation of the phenomena in detail, and recent experiments of emulsion chamber with large area are being carried out at high mountain altitudes by several groups in the world
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