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排序方式: 共有149条查询结果,搜索用时 31 毫秒
51.
Langford NK Weinhold TJ Prevedel R Resch KJ Gilchrist A O'Brien JL Pryde GJ White AG 《Physical review letters》2005,95(21):210504
We demonstrate a new architecture for an optical entangling gate that is significantly simpler than previous realizations, using partially polarizing beam splitters so that only a single optical mode-matching condition is required. We demonstrate operation of a controlled-z gate in both continuous-wave and pulsed regimes of operation, fully characterizing it in each case using quantum process tomography. We also demonstrate a fully resolving, nondeterministic optical Bell-state analyzer based on this controlled-z gate. This new architecture is ideally suited to guided optics implementations of optical gates. 相似文献
52.
We report an efficient transient stimulated Raman conversion of high-energy picosecond pulses at 1350 nm into the eye-safe 1500-nm wavelength range by use of a KGd(WO4)2 crystal. The conversion efficiency into either 1503- or 1537-nm radiation (767- or 901-cm(-1) Raman modes, respectively) is measured to be approximately 10% in a single-pass configuration. The transient Raman gain coefficient is found to be approximately 0.8 cm/GW. Simultaneous generation of multiple Raman lines is also observed. 相似文献
53.
Gordon E. Langford Peter Yates Hin Wing Yeung Kin Fai Cheng 《Magnetic resonance in chemistry : MRC》1980,14(6):474-478
The 13C NMR spectra of leonurine hydrochloride and thirteen of its analogues in DMSO-d6 have been analyzed. Changes in the aromatic substituents have no significant effect on the chemical shifts of the side chain methylene carbons indicating that they do not influence the conformation of the latter. Observed deviations from additivity of substituent effects for the methylene carbon chemical shifts suggest that the methylene side chains of these compounds may be more tightly coiled than are the corresponding n-alkanes. In representative cases no change in conformation is evident in 50% aqueous DMSO-d6 solutions, indicating that similar considerations may apply in aqueous media. 相似文献
54.
Continuous-wave passive mode locking of a diode-pumped Nd:KGd(WO(4))(2) laser is demonstrated. The use of a saturable Bragg reflector as the mode-locking element permits the generation of 6.3-ps pulses, assuming a sech(2) pulse shape. An output power of 1 W was obtained, which corresponds to a slope efficiency of 34.5%. 相似文献
55.
56.
The subharmonic bifurcation solution of nonlinear Mathieu's equation and Euler dynamic buckling problems 总被引:2,自引:0,他引:2
A new approach is presented in this paper on the basis of dynamic systems theory. This paper presents the form of a generic
classification of stable response diagrams for the nonlinear Mathieu equation. In addition, a general method is presented
for determining the topological type of the response diagram for a given equation. This method has been successfully applied
to Euler dynamic buckling problems. Some new results are obtained. 相似文献
57.
Alberto Credi Steven J. Langford Anna Prodi J. Fraser Stoddart Margherita Venturi 《Supramolecular chemistry》2013,25(2):303-311
Abstract The spectroscopic and electrochemical properties of two cyclophanes containing one and, respectively, two 2,7-diazapyrenium electron-acceptor units, and of their [2]catenanes with macrocycles containing two dioxybenzene or dioxynaphthalene electrondonor units have been investigated. The absorption spectra of the catenanes show weak and broad bands in the visible region, assigned to charge-transfer (CT) interactions. The very strong and structured fluorescence (298 K) and the structured fluorescence and phosphorescence (77 K) of the diazapyrenium unit are maintained in the two cyclophanes, but they are no longer present in the [2]catenanes, presumably because of a quenching process caused by the lower energy CT excited states. Each diazapyrenium unit undergoes two distinct reduction processes - only the first one of which is fully reversible - that are hardly affected at all when the diazapyrenium units are incorporated in a cyclophane. In the [2]catenanes, the CT interaction displaces the reduction processes of the diazapyrenium units toward more negative potentials. The results obtained for the diazapyrenium and previously investigated 4,4′-bipyridinium salts, selected cyclophane derivatives, and some [2]catenanes obtained by interlocking the cyclophanes with macrocycles containing two dioxyaromatic electron-donor units are compared and discussed. 相似文献
58.
Sheshanath V. Bhosale Mohan B. Kalyankar Santosh V. Nalage Sidhanath V. Bhosale Cecilia H. Lalander Steven J. Langford 《Supramolecular chemistry》2013,25(8):563-569
The self-assembly of a simple tetraalkyl-substituted protoporphyrin derivative into fibril wire-like nanostructures from CHCl3/cyclohexane solvent mixes is explored. The protoporphyrin IX derivative is synthesised in two efficient steps by amidation of the two propylenic acid groups followed by a cross metathesis of the vinyl groups using Grubbs' second-generation catalyst. The self-assembly of the functionalised protoporphyrin is sensitive to solvent and under favourable conditions forms ‘nanowires’ of micrometre length. The nanowires were characterised by absorption and fluorescence spectroscopy, transmission electron microscopy and atomic force microscopy. 相似文献
59.
Caitlin R. Langford David W. Johnson Neil R. Cameron 《Macromolecular rapid communications》2015,36(9):834-839
Emulsion‐templated highly porous polymers (polyHIPEs), containing distinct regions differing in composition, morphology, and/or properties, are prepared by the simultaneous polymerization of two high internal phase emulsions (HIPEs) contained within the same mould. The HIPEs are placed together in the mould and subjected to thiol‐acrylate photopolymerization. The resulting polyHIPE material is found to contain two distinct semicircular regions, reflecting the composition of each HIPE. The original interface between the two emulsions becomes a copolymerized band between 100 and 300 μm wide, which is found to be mechanically robust. The separate polyHIPE layers are distinguished from one another by their differing average void diameter, chemical composition, and extent of contraction upon drying.
60.
Amy C. Smith Lorena D. Narvaez Bridget G. Akins Moses M. Langford Thomas Gary Victoria J. Geisler 《合成通讯》2013,43(23):4187-4192
We report the use of catalyst, sulfuric acid supported on silica-gel, as promising method for facile, high yielding, regioselective syntheses of mononitrated polycyclic aromatic hydrocarbons, 6-nitrochrysene, 1-nitropyrene, 1-nitronaphthalene, 2-nitrofluorene, 3-nitrofluoranthene, and 9-nitroanthracene. 相似文献