Large four-wave mixing of spatially extended excitonic states in thin GaAs layers

We study the size dependence of the nonlinear response of weakly confined excitons for the size region beyond the long wavelength approximation regime. The observed degenerate-four-wave mixing signal of GaAs thin layers exhibits an anomalous size dependence, where the signal is resonantly enhanced at a particular thickness region. The theoretical analysis elucidates that this enhancement is due to the size-resonant enhancement of the internal field with a spatial structure relevant to the nondipole-type excitonic state. These results establish the formerly proposed new type of size dependence of nonlinear response due to the nonlocality induced double resonance.     

Chronopotentiometric determination of the outer-sphere association constants of substitution-inert metal complexes

Summary A new method for the determination of association constants by the measurement of chronopotentiometric transition time has been developed and applied to the study on the outer-sphere association of some substitution-inert complex cations with sulphate ions. The association constants were determined from the change in transition time as function of the concentration of sulphate ions at ionic strength 0.1 (NaClO₄) and 25° C: 93 ±8 for [Co(NH₃)₆]³⁺SO₄ ^2–, 99 ±15 for [Co(en)₃]³⁺SO₄ ^2–, 61 ±7 for [Cr(NH₃)₆]³⁺SO₄ ^2– and 58 ±8 for [Cr(en)₃]³⁺SO₄ ^2–. The ratios of the diffusion coefficients of the univalent ion-pairs and tervalent substitution-inert complex cations were also obtained. From these ratios the diffusion coefficients of the univalent ion-pairs were calculated, which were found to differ not greatly from those of univalent complex ions with similar structures.

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Zusammenfassung Eine neue Methode zur Bestimmung von Assoziationskonstanten aus den Transitionszeiten chronopotentiometrischer Messungen wurde entwickelt. Sie wurde zur Untersuchung der Assoziation von Sulfationen in zweiter Sphäre an koordinativ abgesättigten Komplex-Kationen herangezogen. Die Assoziationskonstanten wurden aus der Abhängigkeit der Transitionszeit von der Sulfatkonzentration in Medien der Ionenstärke 0,1 (NaClO₄) und bei 25° C bestimmt. Man erhält folgende Werte: 93±8 für [Co(NH₃)₆]³⁺SO₄ ^2–, 99±15 für [Co(en)₃]³⁺SO₄ ^2–, 61±7 für [Cr(NH₃)₆]³⁺SO₄ ^2– und 58±8 für [Cr(en)₃]³⁺SO₄ ^2–. Die Verhältnisse der Diffusionskoeffizienten der einwertigen Ionenpaare zu denen der dreiwertigen Komplex-Kationen wurden ebenfalls bestimmt. Aus diesen Verhältnissen lassen sich die Diffusionskoeffizienten der Ionenpaare berechnen. Man erhält eine gute Übereinstimmung mit den Werten für einwertige Komplexionen mit ähnlicher Struktur.

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Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday.     

High-fidelity teleportation beyond the no-cloning limit and entanglement swapping for continuous variables

We experimentally demonstrate continuous-variable quantum teleportation beyond the no-cloning limit. We teleport a coherent state and achieve the fidelity of 0.70 +/- 0.02 that surpasses the no-cloning limit of 2/3. Surpassing the limit is necessary to transfer the nonclassicality of an input quantum state. By using our high-fidelity teleporter, we demonstrate entanglement swapping, namely, teleportation of quantum entanglement, as an example of transfer of nonclassicality.     

Beam-polarization asymmetries for the p(gamma-->, K+)Lambda and p(gamma-->, K+)Sigma(0) reactions for E(gamma)=1.5-2.4 GeV

Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured for the first time for E(gamma)=1.5-2.4 GeV and 0.6相似文献   

A function space model approach to the rational evaluation subgroups

Let f : U → X be a map from a connected nilpotent space U to a connected rational space X. The evaluation subgroup G _*(U, X; f), which is a generalization of the Gottlieb group of X, is investigated. The key device for the study is an explicit Sullivan model for the connected component containing f of the function space of maps from U to X, which is derived from the general theory of such a model due to Brown and Szczarba (Trans Am Math Soc 349, 4931–4951, 1997). In particular, we show that non Gottlieb elements are detected by analyzing a Sullivan model for the map f and by looking at non-triviality of higher order Whitehead products in the homotopy group of X. The Gottlieb triviality of a fibration in the sense of Lupton and Smith (The evaluation subgroup of a fibre inclusion, 2006) is also discussed from the function space model point of view. Moreover, we proceed to consideration of the evaluation subgroup of the fundamental group of a nilpotent space. In consequence, the first Gottlieb group of the total space of each S ¹-bundle over the n-dimensional torus is determined explicitly in the non-rational case.