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31.
Ericsson M Achilles D Barreiro JT Branning D Peters NA Kwiat PG 《Physical review letters》2005,94(5):050401
Geometric phase may enable inherently fault-tolerant quantum computation. However, due to potential decoherence effects, it is important to understand how such phases arise for mixed input states. We report the first experiment to measure mixed-state geometric phases in optics, using a Mach-Zehnder interferometer, and polarization mixed states that are produced in two different ways: decohering pure states with birefringent elements; and producing a nonmaximally entangled state of two photons and tracing over one of them, a form of remote state preparation. 相似文献
32.
Didierjean J Castaing M Balembois F Georges P Perrodin D Fourmigué JM Lebbou K Brenier A Tillement O 《Optics letters》2006,31(23):3468-3470
We present optical characterization and laser results achieved with single-crystal fibers directly grown by the micro-pulling-down technique. We investigate the spectroscopic and optical quality of the fiber, and we present the first laser results. We achieved a cw laser power of 10 W at 1064 nm for an incident pump power of 60 W at 808 nm and 360 kW peak power for 12 ns pulses at 1 kHz in the Q-switched regime. It is, to the best of our knowledge, the highest laser power ever achieved with directly grown single-crystal fibers. 相似文献
33.
We report on the characterization of an InP/InGaAsP-material-based microdisk resonator optical filter. The originality here is constituted by the use of a localized control electrode that is used for the tuning of the resonance wavelength of the filter via the injection of a driving current. Tuning of the resonance wavelength close to 8 nm has been experimentally achieved for a drive current of 80 mA. 相似文献
34.
Anke Hagen Marie Lund Traulsen Wolff‐Ragnar Kiebach Bjoern Sejr Johansen 《Journal of synchrotron radiation》2012,19(3):400-407
Solid oxide fuel cells (SOFCs) are able to produce electricity and heat from hydrogen‐ or carbon‐containing fuels with high efficiencies and are considered important cornerstones for future sustainable energy systems. Performance, activation and degradation processes are crucial parameters to control before the technology can achieve breakthrough. They have been widely studied, predominately by electrochemical testing with subsequent micro‐structural analysis. In order to be able to develop better SOFCs, it is important to understand how the measured electrochemical performance depends on materials and structural properties, preferably at the atomic level. A characterization of these properties under operation is desired. As SOFCs operate at temperatures around 1073 K, this is a challenge. A spectroelectrochemical cell was designed that is able to study SOFCs at operating temperatures and in the presence of relevant gases. Simultaneous spectroscopic and electrochemical evaluation by using X‐ray absorption spectroscopy and electrochemical impedance spectroscopy is possible. 相似文献
35.
Hybrid DFT/MM methods have been used to investigate the electronic and geometric properties of the microporous titanosilicate ETS-10. A comparison of finite length and periodic models demonstrates that band gap energies for ETS-10 can be well represented with relatively small cluster models. Optimization of finite clusters leads to different local geometries for bulk and end sites, where the local bulk TiO6 geometry is in good agreement with recent experimental results. Geometry optimizations reveal that any asymmetry within the axial O-Ti-O chain is negligible. The band gap in the optimized model corresponds to a O(2p) --> Tibulk(3d) transition. The results suggest that the three Ti atom, single chain, symmetric, finite cluster is an effective model for the geometric and electronic properties of bulk and end TiO6 groups in ETS-10. 相似文献
36.
Emi Evangelio Dr. Marie‐Laure Bonnet Dr. Miquel Cabañas Dr. Motohiro Nakano Dr. Jean‐Pascal Sutter Dr. Andrea Dei Prof. Vincent Robert Dr. Daniel Ruiz‐Molina Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(22):6666-6677
The different thermally induced intermolecular electron transfer (IET) processes that can take place in the series of complexes [M(Cat‐N‐BQ)(Cat‐N‐SQ)]/[M(Cat‐N‐BQ)2], for which M=Co ( 2 ), Fe ( 3 ) and Ni( 4 ), and Cat‐N‐BQ and Cat‐N‐SQ denote the mononegative (Cat‐N‐BQ?) or dinegative (Cat‐N‐SQ2?) radical forms of the tridentate Schiff‐base ligand 3,5‐di‐tert‐butyl‐1,2‐quinone‐1‐(2‐hydroxy‐3,5‐di‐tert‐butylphenyl)imine, have been studied by variable‐temperature UV/Vis and NMR spectroscopies. Depending on the metal ion, rather different behaviors are observed. Complex 2 has been found to be one of the few examples so far reported to exhibit the coexistence of two thermally induced electron transfer processes, ligand‐to‐metal (IETLM) and ligand‐to‐ligand (IETLL). IETLL was only found to take place in complex 3 , and no IET was observed for complex 4 . Such experimental studies have been combined with ab initio wavefunction‐based CASSCF/CASPT2 calculations. Such a strategy allows one to solicit selectively the speculated orbitals and to access the ground states and excited‐spin states, as well as charge‐transfer states giving additional information on the different IET processes. 相似文献
37.
Tyrsted C Pauw BR Jensen KM Becker J Christensen M Iversen BB 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(18):5759-5766
Understanding nanoparticle-formation reactions requires multi-technique in situ characterisation, since no single characterisation technique provides adequate information. Here, the first combined small-angle X-ray scattering (SAXS)/wide-angle X-ray scattering (WAXS)/total-scattering study of nanoparticle formation is presented. We report on the formation and growth of yttria-stabilised zirconia (YSZ) under the extreme conditions of supercritical methanol for particles with Y(2)O(3) equivalent molar fractions of 0, 4, 8, 12 and 25 %. Simultaneous in situ SAXS and WAXS reveals a quick formation (seconds) of sub-nanometre amorphous material forming larger agglomerates with subsequent slow crystallisation (minutes) into nanocrystallites. The amount of yttria dopant is shown to strongly affect the crystallite size and unit-cell dimensions. At yttria-doping levels larger than 8 %, which is known to be the stoichiometry with maximum ionic conductivity, the strain on the crystal lattice is significantly increased. Time-resolved nanoparticle size distributions are calculated based on whole-powder-pattern modelling of the WAXS data, which reveals that concurrent with increasing average particle sizes, a broadening of the particle-size distributions occur. In situ total scattering provides structural insight into the sub-nanometre amorphous phase prior to crystallite growth, and the data reveal an atomic rearrangement from six-coordinated zirconium atoms in the initial amorphous clusters to eight-coordinated zirconia atoms in stable crystallites. Representative samples prepared ex situ and investigated by transmission electron microscopy confirm a transformation from an amorphous material to crystalline nanoparticles upon increased synthesis duration. 相似文献
38.
A new PN2S ligand, N-[2-(diphenylphosphino)phenyl]-2-[(S-trityl)acetylamino]ethanamide [Ph-P(Ph2)N2S(Trt)], was synthesised and reacted with ReV precursors. The reaction of both tritylated and detritylated ligands with ReOCl3(PPh3)2 gave the same expected neutral complex [ReO{Ph-P(Ph2)N2S}] (4) in good yield. An unexpected neutral and diamagnetic species, [ReN{Ph-P(Ph2)N2S(Trt)}] (5), has been isolated during the complexation of the tritylated ligand with ReNCl2(PPh3)2. The complexes, characterized by classical spectroscopic methods and X-ray analysis for 4, are the first examples of neutral semi-rigid-PN2S rhenium(V) complexes. 相似文献
39.
40.
Artur R. Stefankiewicz Jean‐Marie Lehn Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(11):2500-2503
A sensitive magnetic nanoprobe : Hydrogen‐bonding interactions are reflected with great sensitivity in the 1H NMR spectra of a high‐spin multinuclear Fe4II [2×2] grid‐type complex (see scheme) and the measured shifts can be used to evaluate the hydrogen‐bond donating ability. The grid complex also represents a prototype of a very sensitive magnetic nanoreceptor for the detection of very small changes around a magnetic center.