165 research outputs found
A scheme for tunable quantum phase gate and effective preparation of graph-state entanglement
A scheme is presented for realizing a quantum phase gate with three-level
atoms, solid-state qubits--often called artificial atoms, or ions that share a
quantum data bus such as a single mode field in cavity QED system or a
collective vibrational state of trapped ions. In this scheme, the conditional
phase shift is tunable and controllable via the total effective interaction
time. Furthermore, we show that the method can be used for effective
preparation of graph-state entanglement, which are important resources for
quantum computation, quantum error correction, studies of multiparticle
entanglement, fundamental tests of non-locality and decoherence.Comment: 7 pages, 5 figure
A second orthorhombic polymorph of 2-(pyridin-4-ylmethoxy)phenol
The crystal structure of the title compound, C12H11NO2, represents a new orthorhombic polymorph II of the previously reported orthorhombic form I [Zhang et al. (2009 ▶) Acta Cryst. E65, o3160]. In polymorph II, the six-membered rings form a dihedral angle of 13.8 (1)° [71.6 (1)° in I], and O—H⋯N hydrogen bonds link molecules into chains along [100], whereas the crystal structure of I features hydrogen-bonded centrosymmetric dimers
High visibility on-chip quantum interference of single surface plasmons
Quantum photonic integrated circuits (QPICs) based on dielectric waveguides
have been widely used in linear optical quantum computation. Recently, surface
plasmons have been introduced to this application because they can confine and
manipulate light beyond the diffraction limit. In this study, the on-chip
quantum interference of two single surface plasmons was achieved using
dielectric-loaded surface-plasmon-polariton waveguides. The high visibility
(greater than 90%) proves the bosonic nature of single plasmons and emphasizes
the feasibility of achieving basic quantum logic gates for linear optical
quantum computation. The effect of intrinsic losses in plasmonic waveguides
with regard to quantum information processing is also discussed. Although the
influence of this effect was negligible in the current experiment, our studies
reveal that such losses can dramatically reduce quantum interference visibility
in certain cases; thus, quantum coherence must be carefully considered when
designing QPIC devices.Comment: 6 pages, 4 figure
Evolution characteristics analysis of pressure-arch in a double-arch tunnel
Kako bi se osigurala osnova za pojačanje konstrukcije i sigurnost izgradnje tunela s dvostrukim svodom, od teorijske i praktične vrijednosti je analizirati morfološku karakterizaciju, proces razvoja i asimetrični učinak tlačnog svoda u tunelu s dvostrukim svodom. Na temelju opisa graničnih parametara tlačnog svoda u tunelu s dvostrukim svodom, kao istraživački objekt uzet je tunel autoceste s dvostrukim svodom iskopan na dubini od 80 m, te je izrađen numerički proračunski model tunela s dvostrukim svodom uporabom FLAC3D, a potom je analiziran morfološki razvoj tlačnog svoda induciran iskopom korak-po-korak. Rezultati su pokazali da tlačni svod tunela s dvostrukim svodom pokazuje karakteristike asimetrične distribucije koja se postupno smanjuje od lijevog tunela ka desnom tunelu, da rasipanje energije deformacije tunela s dvostrukim svodom od lijevog tunela ka desnom tunelu ide od visokog do niskog, te da su nelinearne odzivne karakteristike u različitim sekvencama iskopa osjetljive na promjene u stanju naprezanja. Rezultatima je omogućena osnova za konstrukcije pojačane kamenom i sigurnost u izgradnji tunela s dvostrukim svodom.In order to provide a basis for the reinforcement design and construction safety of the double-arch tunnel, it is of theoretical and practical value to analyse the morphological characterization, the evolution process and the skewed effect of the pressure-arch in a double-arch tunnel. Based on the descriptions of the boundary parameters of the pressure-arch in a double-arch tunnel, taking the 80 m buried depth double-arch highway tunnel as the research object, the numerical calculation model of the double-arch tunnel was built by using FLAC3D, and then the morphological evolution of the pressure-arch induced by step-by-step excavation was analysed. The results showed that the pressure-arch of the double-arch tunnel displayed the skewed distribution characteristics which were gradually diminishing from the left tunnel to the right tunnel, the strain energy dissipation of the double-arch tunnel from the left tunnel to the right tunnel was from high to low, and the nonlinear response characteristics in different excavation sequences were sensitive to the changes of the stress state. The results provided a basis for the rock reinforcement design and safety construction of double-arch tunnel
Evaluation of Toxoplasma gondii as a live vaccine vector in susceptible and resistant hosts
<p>Abstract</p> <p>Background</p> <p><it>Toxoplasma gondii </it>has been shown to trigger strong cellular immune responses to heterologous antigens expressed by the parasite in the inbred mouse model <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. We studied the immune response induced by <it>T. gondii </it>as an effective vaccine vector in chickens and rabbits.</p> <p>Results</p> <p><it>T. gondii </it>RH strain was engineered to express the yellow fluorescent protein (YFP) in the cytoplasm. A subcutaneous injection of the transgenic <it>T. gondii </it>YFP in chickens afforded partial protection against the infection of transgenic <it>E. tenella </it>YFP. <it>T. gondii </it>YFP induced low levels of antibodies to YFP in chickens, suggesting that YFP specific cellular immune response was probably responsible for the protective immunity against <it>E. tenella </it>YFP infection. The measurement of T-cell response and IFN-γ production further confirmed that YFP specific Th1 mediated immune response was induced by <it>T. gondii </it>YFP in immunized chickens. The transgenic <it>T. gondii </it>stimulated significantly higher YFP specific IgG titers in rabbits than in chickens, suggesting greater immunogenicity in a <it>T. gondii </it>susceptible species than in a resistant species. Priming with <it>T. gondii </it>YFP and boosting with the recombinant YFP can induce a strong anti-YFP antibody response in both animal species.</p> <p>Conclusions</p> <p>Our findings suggest that <it>T. gondii </it>can be used as an effective vaccine vector and future research should focus on exploring avirulent no cyst-forming strains of <it>T. gondii </it>as a live vaccine vector in animals.</p
Does PGA external stenting reduce compliance mismatch in venous grafts?
BACKGROUND: Autogenous vein grafting is widely used in regular bypassing procedures. Due to its mismatch with the host artery in both mechanical property and geometry, the graft often over expands under high arterial blood pressure and forms a step-depth where eddy flow develops, thus causing restenosis, fibrous graft wall, etc. External stents, such as sheaths being used to cuff the graft, have been introduced to eliminate these mismatches and increase the patency. Although histological and immunochemical studies have shown some positive effects of the external stent, the mechanical mismatch under the protection of an external stent remains poorly analyzed. METHODS: In this study, the jugular veins taken from hypercholesterolemic rabbits were transplanted into the carotid arteries, and non-woven polyglycolic acid (PGA) fabric was used to fabricate the external stents to study the effect of the biodegradable external stent. Eight weeks after the operation, the grafts were harvested to perform mechanical tests and histological examinations. An arc tangent function was suggested to describe the relationship between pressure and cross-sectional area to analyse the compliance of the graft. RESULTS: The results from the mechanical tests indicated that grafts either with or without external stents displayed large compliance in the low-pressure range and were almost inextensible in the high-pressure range. This was very different from the behavior of the arteries or veins in vivo. The data from histological tests showed that, with external stents, collagen fibers were more compact, whilst those in the graft without protection were looser and thicker. No elastic fiber was found in either kind of grafts. Furthermore, grafts without protection were over-expanded which resulted in much bigger cross-sectional areas. CONCLUSION: The PGA external extent contributes little to the reduction of the mechanical mismatch between the graft and its host artery while remodeling develops. For the geometric mismatch, it reduces the cross-section area, therefore matching with the host artery much better. Although there are some positive effects, conclusively the PGA is not an ideal material for external stent.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Storage of multiple single-photon pulses emitted from a quantum dot in a solid-state quantum memory
Quantum repeaters are critical components for distributing entanglement over
long distances in presence of unavoidable optical losses during transmission.
Stimulated by Duan-Lukin-Cirac-Zoller protocol, many improved quantum-repeater
protocols based on quantum memories have been proposed, which commonly focus on
the entanglement-distribution rate. Among these protocols, the elimination of
multi-photons (multi-photon-pairs) and the use of multimode quantum memory are
demonstrated to have the ability to greatly improve the
entanglement-distribution rate. Here, we demonstrate the storage of
deterministic single photons emitted from a quantum dot in a
polarization-maintaining solid-state quantum memory; in addition,
multi-temporal-mode memory with , and narrow single-photon pulses
is also demonstrated. Multi-photons are eliminated, and only one photon at most
is contained in each pulse. Moreover, the solid-state properties of both
sub-systems make this configuration more stable and easier to be scalable. Our
work will be helpful in the construction of efficient quantum repeaters based
on all-solid-state devicesComment: Published version, including supplementary materia
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