459 research outputs found
Dilute Multi Alpha Cluster States in Nuclei
Dilute multi cluster condensed states with spherical and axially
deformed shapes are studied with the Gross-Pitaevskii equation and Hill-Wheeler
equation, where the cluster is treated as a structureless boson.
Applications to self-conjugate nuclei show that the dilute
states of C to Ca with appear in the energy region
from threshold up to about 20 MeV, and the critical number of bosons
that the dilute system can sustain as a self-bound nucleus is
estimated roughly to be . We discuss the characteristics of the
dilute states with emphasis on the dependence of their energies
and rms radii.Comment: 44 pages, 8 figure
Inhibition of a nutritional endosymbiont by glyphosate abolishes mutualistic benefit on cuticle synthesis in Oryzaephilus surinamensis
Interwell coupling effect in Si/SiGe quantum wells grown by ultra high vacuum chemical vapor deposition
Si/Si0.66Ge0.34coupled quantum well (CQW) structures with different barrier thickness of 40, 4 and 2 nm were grown on Si substrates using an ultra high vacuum chemical vapor deposition (UHV-CVD) system. The samples were characterized using high resolution x-ray diffraction (HRXRD), cross-sectional transmission electron microscopy (XTEM) and photoluminescence (PL) spectroscopy. Blue shift in PL peak energy due to interwell coupling was observed in the CQWs following increase in the Si barrier thickness. The Si/SiGe heterostructure growth process and theoretical band structure model was validated by comparing the energy of the no-phonon peak calculated by the 6 + 2-bandk·pmethod with experimental PL data. Close agreement between theoretical calculations and experimental data was obtained
Measurement of forward neutral pion transverse momentum spectra for = 7TeV proton-proton collisions at LHC
The inclusive production rate of neutral pions in the rapidity range greater
than has been measured by the Large Hadron Collider forward (LHCf)
experiment during LHC \,TeV proton-proton collision operation in
early 2010. This paper presents the transverse momentum spectra of the neutral
pions. The spectra from two independent LHCf detectors are consistent with each
other and serve as a cross check of the data. The transverse momentum spectra
are also compared with the predictions of several hadronic interaction models
that are often used for high energy particle physics and for modeling
ultra-high-energy cosmic-ray showers.Comment: 18 Pages, 10 figures, submitted to Phys. Rev.
Quantum Information Processing with Ferroelectrically Coupled Quantum Dots
I describe a proposal to construct a quantum information processor using
ferroelectrically coupled Ge/Si quantum dots. The spin of single electrons form
the fundamental qubits. Small (<10 nm diameter) Ge quantum dots are optically
excited to create spin polarized electrons in Si. The static polarization of an
epitaxial ferroelectric thin film confines electrons laterally in the
semiconductor; spin interactions between nearest neighbor electrons are
mediated by the nonlinear process of optical rectification. Single qubit
operations are achieved through "g-factor engineering" in the Ge/Si structures;
spin-spin interactions occur through Heisenberg exchange, controlled by
ferroelectric gates. A method for reading out the final state, while required
for quantum computing, is not described; electronic approaches involving single
electron transistors may prove fruitful in satisfying this requirement.Comment: 10 pages, 3 figure
An addressable quantum dot qubit with fault-tolerant control fidelity
Exciting progress towards spin-based quantum computing has recently been made
with qubits realized using nitrogen-vacancy (N-V) centers in diamond and
phosphorus atoms in silicon, including the demonstration of long coherence
times made possible by the presence of spin-free isotopes of carbon and
silicon. However, despite promising single-atom nanotechnologies, there remain
substantial challenges in coupling such qubits and addressing them
individually. Conversely, lithographically defined quantum dots have an
exchange coupling that can be precisely engineered, but strong coupling to
noise has severely limited their dephasing times and control fidelities. Here
we combine the best aspects of both spin qubit schemes and demonstrate a
gate-addressable quantum dot qubit in isotopically engineered silicon with a
control fidelity of 99.6%, obtained via Clifford based randomized benchmarking
and consistent with that required for fault-tolerant quantum computing. This
qubit has orders of magnitude improved coherence times compared with other
quantum dot qubits, with T_2* = 120 mus and T_2 = 28 ms. By gate-voltage tuning
of the electron g*-factor, we can Stark shift the electron spin resonance (ESR)
frequency by more than 3000 times the 2.4 kHz ESR linewidth, providing a direct
path to large-scale arrays of addressable high-fidelity qubits that are
compatible with existing manufacturing technologies
Cellular Tropism, Population Dynamics, Host Range and Taxonomic Status of an Aphid Secondary Symbiont, SMLS (Sitobion miscanthi L Type Symbiont)
SMLS (Sitobion miscanthi L type symbiont) is a newly reported aphid secondary symbiont. Phylogenetic evidence from molecular markers indicates that SMLS belongs to the Rickettsiaceae and has a sibling relationship with Orientia tsutsugamushi. A comparative analysis of coxA nucleotide sequences further supports recognition of SMLS as a new genus in the Rickettsiaceae. In situ hybridization reveals that SMLS is housed in both sheath cells and secondary bacteriocytes and it is also detected in aphid hemolymph. The population dynamics of SMLS differ from those of Buchnera aphidicola and titer levels of SMLS increase in older aphids. A survey of 13 other aphids reveals that SMLS only occurs in wheat-associated species
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