62 research outputs found
Phosphorus Nitride P3N5
Pure, stoichiometric, hydrogen-free, and crystalline phosphorus nitride P3N5 has been obtained for the first time by reaction of (PNCl2)3 and NH4Cl between 770 and 1050 K. The compound has been characterized by elemental analyses, 31P and 15N MAS NMR, EXAFS, IR spectroscopy, X-ray powder diffraction, and electron microscopy. In the solid a three-dimensional cross-linked network structure of corner sharing PN4 tetrahedra has been identified with 2/5 of the nitrogen atoms bonded to three P atoms and 3/5 of the nitrogen atoms bonded to two P atoms. By electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM) two distinguishable modifications α-P3N5 and β-P3N5 have been identified which differentiate only by the stacking order of identical sheets similar to the polytypes of SiC
Detecting multiparticle entanglement of Dicke states
Recent experiments demonstrate the production of many thousands of neutral
atoms entangled in their spin degrees of freedom. We present a criterion for
estimating the amount of entanglement based on a measurement of the global
spin. It outperforms previous criteria and applies to a wide class of entangled
states, including Dicke states. Experimentally, we produce a Dicke-like state
using spin dynamics in a Bose-Einstein condensate. Our criterion proves that it
contains at least genuine 28-particle entanglement. We infer a generalized
squeezing parameter of -11.4(5) dB.Comment: 5 pages, 4 figure
Silicon phosphorus nitride, the first ternary compound in the silicon-phosphorus-nitrogen system
Spontaneous symmetry breaking in spinor Bose-Einstein condensates
We present an analytical model for the theoretical analysis of spin dynamics
and spontaneous symmetry breaking in a spinor Bose-Einstein condensate (BEC).
This allows for an excellent intuitive understanding of the processes and
provides good quantitative agreement with experimental results in Phys. Rev.
Lett. 105, 135302 (2010). It is shown that the dynamics of a spinor BEC
initially prepared in an unstable Zeeman state mF=0 (|0>) can be understood by
approximating the effective trapping potential for the state |+-1> with a
cylindrical box potential. The resonances in the creation efficiency of these
atom pairs can be traced back to excitation modes of this confinement. The
understanding of these excitation modes allows for a detailed characterization
of the symmetry breaking mechanism, showing how a twofold spontaneous breaking
of spatial and spin symmetry can occur. In addition a detailed account of the
experimental methods for the preparation and analysis of spinor quantum gases
is given.Comment: 12 pages, 14 figure
Towards medhub: A Self-Service Platform for Analysts and Physicians
Combining clinical and omics data can improve both daily clinical routines
and research to gain more insights into complex medical procedures. We present
the results of our first phase in a multi-year collaboration with analysts and
physicians aiming at improved inter-disciplinary biomarker identification. We
also outline our user-centered approach along its challenges, describe the
intermediate technical artifacts that serve as a basis for summative and
formative evaluation for the second project phase. Finally, we sketch the road
ahead and how we intend to combine visualization research with user-centered
design through problem-based prioritization.Comment: 2 + 1 page
Detecting metrologically useful entanglement in the vicinity of Dicke states
We present a method to verify the metrological usefulness of noisy Dicke
states of a particle ensemble with only a few collective measurements, without
the need for a direct measurement of the sensitivity. Our method determines the
usefulness of the state for the usual protocol for estimating the angle of
rotation with Dicke states, which is based on the measurement of the second
moment of a total spin component. It can also be used to detect entangled
states that are useful for quantum metrology. We test our approach on recent
experimental results.Comment: 17 pages including 4 figures; v2: Sec. IV with further numerical
examples added, Appendix added; v3: published versio
Anionic N-heterocyclic carbenes derived from sydnone imines such as molsidomine. Trapping reactions with selenium, palladium, and gold
The sydnone imines Molsidomine and 5-(benzoylimino)-3-(2-methoxyphenyl)-1,2,3-oxadiazolium-2-ide gave anionic N-heterocyclic carbenes on deprotonation at C4 which were trapped as methylated selenium adducts, gold complexes (X-ray analysis) as well as palladium complexes (X-ray analysis). The C-13 NMR resonance frequencies of the carbene carbon atom are extremely shifted upfield and appear at delta = 142.1 ppm (Molsidomine carbene) and delta = 159.8 ppm (sydnone imine carbene). The Pd complexes were applied as catalysts in Suzuki-Miyaura and Sonogashira-Hagihara cross-coupling reactions. (C) 2017 Elsevier Ltd. All rights reserved.Peer reviewe
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