螺旋光纤系统中非绝热条件几何相移

由于绝热条件几何相位量子逻辑门存在非绝热差错与退相干差错这一冲突，因此在拓扑量子计算中需要设计非绝热条件几何相门，以克服这一不足.证明螺旋光纤系统内光子有效哈密顿量恰好是一个Wang Matsumoto型哈密顿量，因此螺旋光纤系统能自动产生非绝热条件几何相移.同时还证明在螺旋光纤方案中，由极化光子与螺旋光纤相互作用哈密顿量所导致的动力学相位为零（这正是拓扑量子计算所要求的），以及在螺旋光纤系统中可以通过控制极化光子初始波矢，从而较容易获得条件初始态.总之，螺旋光纤系统方案能自动满足Wang与Matsumoto的核磁共振方案中为实现非绝热条件几何相移所提出的全部条件与要求. 关键词： 几何相位 螺旋光纤系统 Wang Matsumoto型哈密顿量 拓扑量子计算     

Novel 3‐hydroxypropyl‐bonded phase by direct hydrosilylation of allyl alcohol on amorphous hydride silica

A novel 3‐hydroxypropyl (propanol)‐bonded silica phase has been prepared by hydrosilylation of allyl alcohol on a hydride silica intermediate, in the presence of platinum (0)‐divinyltetramethyldisiloxane (Karstedt's catalyst). The regio‐selectivity of this synthetic approach had been correctly predicted by previous reports involving octakis(dimethylsiloxy)octasilsesquioxane (Q₈M₈^H) and hydrogen silsesquioxane (T₈H₈), as molecular analogs of hydride amorphous silica. Thus, C‐silylation predominated (～94%) over O‐silylation, and high surface coverages of propanol groups (5 ± 1 μmol/m²) were typically obtained in this work. The propanol‐bonded phase was characterized by spectroscopic (infrared (IR) and solid‐state NMR on silica microparticles), contact angle (on fused‐silica wafers) and CE (on fused‐silica tubes) techniques. CE studies of the migration behavior of pyridine, caffeine, Tris(2,2′‐bipyridine)Ru(II) chloride and lysozyme on propanol‐modified capillaries were carried out. The adsorption properties of these select silanol‐sensitive solutes were compared to those on the unmodified and hydride‐modified tubes. It was found that hydrolysis of the SiH species underlying the immobilized propanol moieties leads mainly to strong ion‐exchange‐based interactions with the basic solutes at pH 4, particularly with lysozyme. Interestingly, and in agreement with water contact angle and electroosmotic mobility figures, the silanol–probe interactions on the buffer‐exposed (hydrolyzed) hydride surface are quite different from those of the original unmodified tube.     

On the aspect of plane of appearance of Jahn-Teller and Renner-Teller intersections in tetra-atomic system—A case study with HCNO+

A search for configuration space with well-defined topological (Berry) phases corresponding to Jahn-Teller (JT) conical intersection (CI) and Renner-Teller (RT) parabolic intersection (PI) in the linear tetra-atomic molecular system on introduction of bending demonstrates the interesting aspect that these potential intersections may appear in the molecular plane as well as out of the molecular plane. While understanding this aspect is important for following the class of phenomena led by potential intersections, till date, studies on molecular systems, including pairs such as (C₂H₂⁺, HCNH) and (N₂H₂⁺, HBNH⁺), have not been able to clarify the issue. The present article includes calculation of nonadiabatic coupling terms involving four low-lying states of slightly bent HCNO⁺, a motivated choice of tetra-atomic with all four different atoms, to study this aspect associated with JT-CI and RT-PI in a slightly bent linear system. The plane of appearance of these effects has been advocated to be related to the electronic configuration of the concerned states of the molecular system.     

Unusually large 254 Atoms Counter-Ion for 5 Atoms [Ge5]2– Cluster

Abstract . With the attempt to synthesize Nb-enclosed germanium Zintl cluster ion in ethylenediamine (en) / toluene solution, the reaction of K₄Ge₉/Na₄Ge₉ with Nb(mes)₂ (mes = mesitylene) gives unexpected 18-crown-6 cleavage product of [K₁₄Na₂(NbO₂)₂(C₈H₁₆O₅)₈](Ge₅) (en) · solv in the form of very air-sensitive, light-brown, plate-like crystals. This unique compound crystallizes in monoclinic Pn (No. 7) space group, the cleavage of crown linked the 14 potassium, 2 sodium, and 2 niobium atoms into the bulky 2+ charged cation, which balances the [Ge₅]^2– anion. This compound represents the rare example of heteronuclear metal alkoxide / Zintl ion hybrid.     

A Small Change in Central Linker Has a Profound Effect in Inducing Columnar Phases of Triazine‐Based Unconventional Dendrimers

Four unconventional triazine‐based dendrimers have been prepared and characterized by ¹H and ¹³C NMR spectroscopies, mass spectrometry, and elemental analysis. Based on DSC studies, polarizing microscopy, and powder XRD, two of these dendrimers, containing linkers with an odd number of carbon atoms, were observed to display columnar liquid–crystalline phases during thermal treatment. However, the other two dendritic analogues, containing linkers with an even number of carbon atoms, were not observed to behave correspondingly. Based on computer simulation, we reasonably assume that the dendrimers with an odd number of carbon atoms in their linkers distort their molecular shape and adopt two isomeric structures due to asymmetrical congestion. This reduces the molecular π–π face‐to‐face interaction, which in turn causes the dendrimers to form columnar LC phases during thermal treatment. However, the dendrimers with an even number of carbon atoms in their linkers have more symmetrical skeletons and do not display any liquid–crystalline phase upon thermal treatment. This new strategy should be applicable for eliciting the columnar liquid–crystalline properties of other types of unconventional dendrimers with rigid frameworks.     

A Combined Metal–Halide/Metal Flux Synthetic Route towards Type‐I Clathrates: Crystal Structures and Thermoelectric Properties of A8Al8Si38 (A=K,Rb, and Cs)

Single‐phase samples of the compounds K₈Al₈Si₃₈ ( 1 ), Rb₈Al₈Si₃₈ ( 2 ), and Cs_7.9Al_7.9Si_38.1 ( 3 ) were obtained with high crystallinity and in good quantities by using a novel flux method with two different flux materials, such as Al and the respective alkali‐metal halide salt (KBr, RbCl, and CsCl). This approach facilitates the removal of the product mixture from the container and also allows convenient extraction of the flux media due to the good solubility of the halide salts in water. The products were analyzed by means of single‐crystal X‐ray structure determination, powder X‐ray and neutron diffraction experiments, ²⁷Al‐MAS NMR spectroscopy measurements, quantum chemical calculations, as well as magnetic and transport measurements (thermal conductivity, electrical resistivity, and Seebeck coefficient). Due to the excellent quality of the neutron diffraction data, the difference between the nuclear scattering factors of silicon and aluminum atoms was sufficient to refine their mixed occupancy at specific sites. The role of variable‐range hopping for the interpretation of the resistivity and the Seebeck coefficient is discussed.     

Nematic Defects and Colloids as Photonic Elements

Birefringent structures in liquid crystalline fluids, such as colloidal assemblies or topological defects, show high potential for use as photonic elements. Here, we present a brief overview of two photonic phenomena originating from coupling light fields with complex birefringent nematic profiles: (i) the generation of vector laser beams from simple Gaussian beams by propagating light along nematic discliantions, and (ii) tunable photonic crystals from blue phase colloidal crystals conditioned by the different underlying symmetries of the particle lattice and the blue phase birefringence. The polarization profile of initially simple linearly polarized Gaussian beams is shown to change into a defect structure at distinct distances travelled along the disclination with the topological invariant (winding number) of the light field and nematic director distinctly coupled. Upon pulsed laser illumination, the nematic discliantions are also shown to split the light pulse into multiple intensity regions. Blue phase I face centred cubic colloidal crystals are shown as examples of tunable photonic crystals, where local band-baps can open by differently combining the symmetries of the two components, e.g. by changing the particle size. The spatial profiles of selected photonic bands in the blue phase colloidal crystals are shown, finding the particles and blue phase double twist cylinders as possible carriers of high-light-intensity regions.     

Dynamic Switching of the Circularly Polarized Luminescence of Disubstituted Polyacetylene by Selective Transmission through a Thermotropic Chiral Nematic Liquid Crystal

The circularly polarized luminescence (CPL) of chiral disubstituted liquid‐crystalline polyacetylene (di‐LCPA) can be dynamically switched and amplified from left‐ to right‐handed CPL and vice versa through the selective transmission of CPL across a thermotropic chiral nematic liquid crystal (N*‐LC) phase. By combining a chiral di‐LCPA CPL‐emitting film with an N*‐LC cell and tuning the selective reflection band of the N*‐LC phase to coincide with the CPL emission band, a CPL‐switchable cell was constructed. The phase change induced by the thermotropic N*‐LC cell by varying the temperature leads to a change in the selective transmission of CPL, which enables the dynamic switching and amplification of CPL. It is anticipated that CPL‐switchable devices might find applications in switchable low‐threshold lasers and optical memory devices.     

Fabrication of Polyhedral Particles from Spherical Colloids and Their Self‐Assembly into Rotator Phases

Particle shape is a critical parameter that plays an important role in self‐assembly, for example, in designing targeted complex structures with desired properties. Over the last decades, an unprecedented range of monodisperse nanoparticle systems with control over the shape of the particles have become available. In contrast, the choice of micrometer‐sized colloidal building blocks of particles with flat facets, that is, particles with polygonal shapes, is significantly more limited. This can be attributed to the fact that in contrast to nanoparticles, the larger colloids are significantly harder to synthesize as single crystals. It is now shown that a very simple building block, such as a micrometer‐sized polymeric spherical colloidal particle, is already enough to fabricate particles with regularly placed flat facets, including completely polygonal shapes with sharp edges. As an illustration that the yields are high enough for further self‐assembly studies, the formation of three‐dimensional rotator phases of fluorescently labelled, micrometer‐sized, and charged rhombic dodecahedron particles was demonstrated. This method for fabricating polyhedral particles opens a new avenue for designing new materials.