419 research outputs found
Optimal simulation of two-qubit Hamiltonians using general local operations
We consider the simulation of the dynamics of one nonlocal Hamiltonian by
another, allowing arbitrary local resources but no entanglement nor classical
communication. We characterize notions of simulation, and proceed to focus on
deterministic simulation involving one copy of the system. More specifically,
two otherwise isolated systems and interact by a nonlocal Hamiltonian
. We consider the achievable space of Hamiltonians such
that the evolution can be simulated by the interaction
interspersed with local operations. For any dimensions of and , and any
nonlocal Hamiltonians and , there exists a scale factor such that
for all times the evolution can be simulated by acting for
time interspersed with local operations. For 2-qubit Hamiltonians and
, we calculate the optimal and give protocols achieving it. The optimal
protocols do not require local ancillas, and can be understood geometrically in
terms of a polyhedron defined by a partial order on the set of 2-qubit
Hamiltonians.Comment: (1) References to related work, (2) protocol to simulate one
two-qudit Hamiltonian with another, and (3) other related results added. Some
proofs are simplifie
A generalized no-broadcasting theorem
We prove a generalized version of the no-broadcasting theorem, applicable to
essentially \emph{any} nonclassical finite-dimensional probabilistic model
satisfying a no-signaling criterion, including ones with ``super-quantum''
correlations. A strengthened version of the quantum no-broadcasting theorem
follows, and its proof is significantly simpler than existing proofs of the
no-broadcasting theorem.Comment: 4 page
A special simplex in the state space for entangled qudits
Focus is on two parties with Hilbert spaces of dimension d, i.e. "qudits". In
the state space of these two possibly entangled qudits an analogue to the well
known tetrahedron with the four qubit Bell states at the vertices is presented.
The simplex analogue to this magic tetrahedron includes mixed states. Each of
these states appears to each of the two parties as the maximally mixed state.
Some studies on these states are performed, and special elements of this set
are identified. A large number of them is included in the chosen simplex which
fits exactly into conditions needed for teleportation and other applications.
Its rich symmetry - related to that of a classical phase space - helps to study
entanglement, to construct witnesses and perform partial transpositions. This
simplex has been explored in details for d=3. In this paper the mathematical
background and extensions to arbitrary dimensions are analysed.Comment: 24 pages, in connection with the Workshop 'Theory and Technology in
Quantum Information, Communication, Computation and Cryptography' June 2006,
Trieste; summary and outlook added, minor changes in notatio
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Validation study of air-sea gas transfer modeling
Laboratory results have demonstrated the importance of bubble plumes to air-water gas transfer (Asher et al., 1994). Bubble plumes enhance gas transfer by disrupting surface films, by directly transporting a gas, and by the creation of turbulence. Models of bubble gas transfer have been developed by different authors (Atkinson, 1973; Memery and Merlivat, 1985; Woolf and Thorpe, 1991) to determine the magnitude of gas transfer due to bubbles. Laboratory measurements of both the gas transfer rate k{sub L}, and the bubble distribution {phi} in a whitecap simulation tank (WST) have allowed these models to be validated and deficiencies in the theoretical assumptions to be explored. In the WST, each bucket tip simulates a wave breaking event. Important tests of these models include whether they can explain the experimentally determined solubility and Schmidt number dependency of k{sub L}, predict the time varying bubble concentrations, predict the evasion-invasion asymmetry, and predict the fraction of k{sub L} due to bubble plumes. Four different models were tested, a steady state model (Atkinson, 1973), a non-turbulence model with constant bubble radius (Memery and Merlivat, 1985), a turbulence model with constant bubble radius (Wolf and Thorpe, 1991), and a turbulence model with varying bubble radius. All models simulated multiple bubble tip cycles. The two turbulence models were run for sufficient tip cycles to generate statistically significant number of eddies ({number_sign}{gt}50) for bubbles affected by turbulence (V{sub B}{le}V{sub T}), found to be at least four tip cycles. The models allowed up to nine gases simultaneously and were run under different conditions of trace and major gas concentrations and partial pressures
Two-, three-, and four-component magnetic multilayer onion nanoparticles based on iron oxides and manganese oxides
Magnetic multilayered, onion-like, heterostructured nanoparticles are interesting model systems for studying magnetic exchange coupling phenomena. In this work, we synthesized heterostructured magnetic nanoparticles composed of two, three, or four components using iron oxide seeds for the subsequent deposition of manganese oxide. The MnO layer was allowed either to passivate fully in air to form an outer layer of Mn3O4 or to oxidize partially to form MnO|Mn3O4 double layers. Through control of the degree of passivation of the seeds, particles with up to four different magnetic layers can be obtained (i.e., FeO|Fe3O4|MnO|Mn3O4). Magnetic characterization of the samples confirmed the presence of the different magnetic layers
Scientific and Technical Assistance for the Deployment of a Flexible Airborne Spectrometer System During C-MAPExp and COMEX
The COMEX (CO2 and MEthane eXperiment) campaign supports the mission definition of CarbonSat and HyspIRI (Hyperspectral Infrared Imager) by providing representative airborne remote sensing data MAMAP (Methane Airborne MAPper) for CarbonSat; the Airborne Visual InfraRed Imaging Spectrometer (Classic & Next Generation) AVIRISC/AVIRISNG for HyspIRI as well as ground-based and airborne insitu data. The objectives of the COMEX campaign activities are (see Campaign Implementation Plan (RD4)): 1. Investigate spatial/spectral resolution tradeoffs for CH4 anomaly detection and flux inversion by comparison of MAMAPderived emission estimates with AVIRIS/AVIRISNG derived data. 2. Evaluate sunglint observation geometry on CH4 retrievals for marine sources. 3. Characterize the effect of Surface Spectral Reflectance (SSR) heterogeneity on trace gas retrievals of CO2 and CH4 for medium and lowresolution spectrometry. 4. Identify benefits from joint SWIR/TIR (ShortWave InfraRed/Thermal InfraRed ) data for trace gas detection and retrieval by comparison of MAMAP and AVIRIS/AVIRISNG NIR/SWIR data with MAKO (Aerospace Corp.)TIR data. The ability to derive emission source strength for a range of strong emitting targets by remote sensing will be evaluated from combined AVIRISNG and MAMAP data, adding significant value to the HyspIRI campaign AVIRISNG dataset. The data will be used to quantify anomalies in atmospheric CO2 and CH4 from strong local greenhouse gas sources e.g. localized industrial complexes, landfills, etc. and to derive CO2 and CH4 emissions estimates from atmospheric gradient measurements. The original campaign concept was developed by University of Bremen and BRI. The COMEX campaign is funded bilaterally by NASA and ESA (European Space Agency). Whereas NASA funds the US part of the project via a contract with Dr. Ira Leifer, BRI (Bubbleology Research International), the contribution of MAMAP to the COMEX campaign is funded by ESA within the COMEXE project and NASA with respect to a 50 percent contribution to the flight-related costs of flying MAMAP on a US aircraft. The Data Acquisition Report (RD9) describes the instrumentation used, the measurements made by the team during the COMEX campaign in May/June 2014 and August/September 2014 in California, and an initial assessment of the data quality
The Role of TLR4 in the Paclitaxel Effects on Neuronal Growth In Vitro
Paclitaxel (Pac) is an antitumor agent that is widely used for treatment of solid cancers. While being effective as a chemotherapeutic agent, Pac in high doses is neurotoxic, specifically targeting sensory innervations. In view of these toxic effects associated with conventional chemotherapy, decreasing the dose of Pac has been recently suggested as an alternative approach, which might limit neurotoxicity and immunosuppression. However, it remains unclear if low doses of Pac retain its neurotoxic properties or might exhibit unusual effects on neuronal cells. The goal of this study was to analyze the concentration-dependent effect of Pac on isolated and cultured DRG neuronal cells from wild-type and TLR4 knockout mice. Three different morphological parameters were analyzed: the number of neurons which developed neurites, the number of neurites per cell and the total length of neurites per cell. Our data demonstrate that low concentrations of Pac (0.1 nM and 0.5 nM) do not influence the neuronal growth in cultures in both wild type and TLR4 knockout mice. Higher concentrations of Pac (1-100 nM) had a significant effect on DRG neurons from wild type mice, affecting the number of neurons which developed neurites, number of neurites per cell, and the length of neurites. In DRG from TLR4 knockout mice high concentrations of Pac showed a similar effect on the number of neurons which developed neurites and the length of neurites. At the same time, the number of neurites per cell, indicating the process of growth cone initiation, was not affected by high concentrations of Pac. Thus, our data showed that Pac in high concentrations has a significant damaging effect on axonal growth and that this effect is partially mediated through TLR4 pathways. Low doses of Pac are devoid of neuronal toxicity and thus can be safely used in a chemomodulation mode. © 2013 Ustinova et al
Variable-Pitch Rectangular Cross-section Radiofrequency Coils for the Nitrogen-14 Nuclear Quadrupole Resonance Investigation of Sealed Medicines Packets
This work was partly funded by a technology transfer award from the Wellcome Trust (U.K.). Additional funding was provided by the European Commission as part of 7th Framework Programme under Grant No. 261670
Differential detection of classical swine fever virus challenge strains in C-strain vaccinated pigs
Quantum dynamics as a physical resource
How useful is a quantum dynamical operation for quantum information
processing? Motivated by this question we investigate several strength measures
quantifying the resources intrinsic to a quantum operation. We develop a
general theory of such strength measures, based on axiomatic considerations
independent of state-based resources. The power of this theory is demonstrated
with applications to quantum communication complexity, quantum computational
complexity, and entanglement generation by unitary operations.Comment: 19 pages, shortened by 3 pages, mainly cosmetic change
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