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showing 10 items of 1359 documents
Programmable linear quantum networks with a multimode fibre
2019
Reconfigurable quantum circuits are fundamental building blocks for the implementation of scalable quantum technologies. Their implementation has been pursued in linear optics through the engineering of sophisticated interferometers. While such optical networks have been successful in demonstrating the control of small-scale quantum circuits, scaling up to larger dimensions poses significant challenges. Here, we demonstrate a potentially scalable route towards reconfigurable optical networks based on the use of a multimode fibre and advanced wavefront-shaping techniques. We program networks involving spatial and polarisation modes of the fibre and experimentally validate the accuracy and ro…
Improving thermoelectric performance of TiNiSn by mixing MnNiSb in the half-Heusler structure
2016
The thermoelectric properties of n type semiconductor, TiNiSn is optimized by partial substitution with metallic, MnNiSb in the half Heusler structure. Herein, we study the transport properties and intrinsic phase separation in the system. The Ti1-xMnxNiSn1-xSbx alloys were prepared by arc-melting and were annealed at temperatures obtained from differential thermal analysis and differential scanning calorimetry results. The phases were characterized using powder X-ray diffraction patterns, energy dispersive X-ray spectroscopy, and differential scanning calorimetry. After annealing the majority phase was TiNiSn with some Ni rich sites and the minority phases was majorly Ti6Sn5, Sn, and MnSn2…
Vortex rings in two-dimensional harmonic traps
2006
We use the configuration interaction technique to study vortex formation in rotating systems of interacting spinless fermions and bosons trapped in a two-dimensional harmonic potential. In the fermionic case, the vortices appear as holes in the Fermi sea and localize in rings. The yrast spectrum is dominated by rigid rotation of the vortex ring, showing periodic oscillations. The Bose system shows a similar yrast spectrum and vortex formation. This can be explained by a one-to-one correspondence of the fermion and boson many-particle configurations. A simple mean-field model can reproduce the oscillations in the yrast spectrum, but fails to explain the localization of vortices.
Tunable and reconfigurable microwave filter by use of a Bragg-grating-based acousto-optic superlattice modulator
2005
We present an all-optical novel configuration for implementing multitap transversal filters by use of a broadband source sliced by fiber Bragg grating arrays generated by propagating an acoustic wave along a strong uniform fiber Bragg grating. The tunability and reconfigurability of the microwave filter are demonstrated.
High-spin states in tetrahedral X4 clusters (X = H, Li, Na, K)
2010
The high-spin electronic states for lithium, sodium, and potassium four-atom clusters were studied. In particular, we performed coupled cluster geometry optimization of the quintet state in tetrahedral geometry. The quintet state of these systems is characterized by having all the valence electron Unpaired, giving rise to the so-called no-pair bonding. Single-point full configuration interaction computations on the equilibrium geometries for the various Clusters are also presented. The analysis of the valence orbitals in a localized representation confirms the importance of the p atomic orbitals to explain this unusual type of bond. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 110: 8…
Small Clusters Made of Helium Atoms
2003
Helium atoms interact very weakly through a van der Waals potential. Nevertheless, they are able to form aggregates or drops with a small number of atoms. This work analyzes the stability of clusters made of 4He atoms, of bosonic nature, clusters made of 3He atoms, of fermionic nature and also mixed aggregates with both kinds of constituents. Some of these drops are predicted to be unstable.
Theory of glass transition in spin glasses, orientational glasses and structural glasses
2008
Theoretical concepts about the glass transition are briefly reviewed, and the test of these ideas by Monte Carlo simulations of simple lattice models is described, with an emphasis on isotropic and anisotropic orientational glasses, and the bond fluctuation model of polymer melts. It is suggested that orientational glasses do have an equilibrium phase transition at zero temperature (in d = 3 dimensions!) only, in contrast to the Ising spin glass which orders at nonzero temperature. A diverging glass correlation length is identified that is responsible for the anomalous slowing down. For the Potts glass, the divergence seems to be exponential, implying that the model is at its lower critical…
Les conditions enseignantes. Politiques éducatives, statuts sociaux et reconfigurations du travail
2018
International audience
Functional consequences of prey acclimation to ocean acidification for the prey and its predator
2016
Ocean acidification is the suite of chemical changes to the carbonate system of seawater as a consequence of anthropogenic carbon dioxide (CO2) emissions. Despite a growing body of evidences demonstrating the negative effects of ocean acidification on marine species, the consequences at the ecosystem level are still unclear. One factor limiting our ability to upscale from species to ecosystem is the poor mechanistic understanding of the functional consequences of the observed effects on organisms. This is particularly true in the context of species interactions. The aim of this work was to investigate the functional consequence of the exposure of a prey (the mussel Brachidontes pharaonis) t…
Symmetry of root and root canal morphology of mandibular incisors: A cone-beam computed tomography study
2019
Background Aim of this study was to analyze the root canal configuration in mandibular central and lateral incisors in vivo using cone-beam computed tomography (CBCT) imaging. Material and methods A total of 487 mandibular central incisors and 491 mandibular lateral incisors from 250 patients were examined using CBCT imaging, previously taken for diagnosis and treatment. The number of roots, root canal system configuration, presence of apical confluences, distance between confluences and radiographic root end, symmetry between left and right elements were recorded and statistically analyzed. Results All the examined teeth presented only one root. No significant differences were found betwee…