6,155 research outputs found
Contextual, Optimal and Universal Realization of the Quantum Cloning Machine and of the NOT gate
A simultaneous realization of the Universal Optimal Quantum Cloning Machine
(UOQCM) and of the Universal-NOT gate by a quantum injected optical parametric
amplification (QIOPA), is reported. The two processes, forbidden in their exact
form for fundamental quantum limitations, are found universal and optimal, and
the measured fidelity F<1 is found close to the limit values evaluated by
quantum theory. This work may enlighten the yet little explored
interconnections of fundamental axiomatic properties within the deep structure
of quantum mechanics.Comment: 10 pages, 2 figure
Measurement and simulation of anisotropic magnetoresistance in single GaAs/MnAs core/shell nanowires
We report four probe measurements of the low field magnetoresistance in
single core/shell GaAs/MnAs nanowires synthesized by molecular beam epitaxy,
demonstrating clear signatures of anisotropic magnetoresistance that track the
field-dependent magnetization. A comparison with micromagnetic simulations
reveals that the principal characteristics of the magnetoresistance data can be
unambiguously attributed to the nanowire segments with a zinc blende GaAs core.
The direct correlation between magnetoresistance, magnetization and crystal
structure provides a powerful means of characterizing individual hybrid
ferromagnet/semiconductor nanostructures.Comment: Submitted to Applied Physics Letters; some typos corrected and a
defective figure replace
Apoptosis in the chorion laeve of term patients with histologic chorioamnionitis.
OBJECTIVE: The balance between cell survival and cell death (apoptosis) is critical during development and may affect organ function. Apoptosis is accelerated in the presence of infection and inflammation in a variety of organ systems. The objective of this investigation was to determine if apoptosis was increased in the chorion laeve of term patients with and without histologic chorioamnionitis. METHODS: Records of placental pathology were reviewed with respect to the presence/absence of histologic chorioamnionitis. Sections from formalin-fixed, paraffin-embedded fetal membrane rolls were stained using the TUNEL method. The proportion of apoptotic nuclei was calculated in seven high-powered fields/section. Those with and without histologic chorioamnionitis were compared. Data were analyzed using the Mann-Whitney U test, with significance defined as p < 0.05. RESULTS: There was no significant difference in demographic or clinical characteristics between the two groups. The chorion laeve from subjects with histologic chorioamnionitis had significantly more apoptotic nuclei when compared to those without chorioamnionitis (11.2% vs. 5%, p = 0.02). CONCLUSION: Apoptosis is more prevalent in the chorion laeve of fetal membranes with histologic chorioamnionitis. This finding suggests that infection/inflammation may impact cell survival within fetal membranes. The implications of these findings warrant further investigation
Lambda's, V's and optimal cloning with stimulated emission
We show that optimal universal cloning of the polarization state of photons
can be achieved via stimulated emission in three-level systems, both of the
Lambda and the V type. We establish the equivalence of our systems with coupled
harmonic oscillators, which permits us to analyze the structure of the cloning
transformations realized. These transformations are shown to be equivalent to
the optimal cloning transformations for qubits discovered by Buzek and Hillery,
and Gisin and Massar. The down-conversion cloner discovered previously by some
of the authors is obtained as a limiting case. We demonstrate an interesting
equivalence between systems of Lambda atoms and systems of pairwise entangled V
atoms. Finally we discuss the physical differences between our photon cloners
and the qubit cloners considered previously and prove that the bounds on the
fidelity of the clones derived for qubits also apply in our situation.Comment: 10 page
Use of ERTS-1 data in identification, classification, and mapping of salt-affected soils in California
There are no author-identified significant results in this report
Monotonic properties of the shift and penetration factors
We study derivatives of the shift and penetration factors of collision theory
with respect to energy, angular momentum, and charge. Definitive results for
the signs of these derivatives are found for the repulsive Coulomb case. In
particular, we find that the derivative of the shift factor with respect to
energy is positive for the repulsive Coulomb case, a long anticipated but
heretofore unproven result. These results are closely connected to the
properties of the sum of squares of the regular and irregular Coulomb
functions; we also present investigations of this quantity.Comment: 13 pages, 1 figur
Generalized Symmetries of Impulsive Gravitational Waves
We generalize previous \cite{AiBa2} work on the classification of
() symmetries of plane-fronted waves with an impulsive profile. Due
to the specific form of the profile it is possible to extend the group of
normal-form-preserving diffeomorphisms to include non-smooth transformations.
This extension entails a richer structure of the symmetry algebra generated by
the (non-smooth) Killing vectors.Comment: 18 pages, latex2e, no figure
Optimal Quantum Cloning via Stimulated Emission
We show that optimal universal quantum cloning can be realized via stimulated
emission. Universality of the cloning procedure is achieved by choosing systems
that have appropriate symmetries. We first discuss a scheme based on stimulated
emission in certain three-level-systems, e.g. atoms in a cavity. Then we
present a way of realizing optimal universal cloning based on stimulated
parametric down-conversion. This scheme also implements the optimal universal
NOT operation.Comment: 4 pages, 3 figure
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