39K and 77Se NMR study of the paraelectric-to-incommensurate phase transition of K2SeO4

Topic B, von Kienlin A, Gölzhäuser A, Haeberlin U, Blinc R. 39K and 77Se NMR study of the paraelectric-to-incommensurate phase transition of K2SeO4. Physical Review, B. 1988;38(13):8625-8632.The 39K quadrupole-coupling and chemical-shift tensors have been determined from the angular dependences of the 39K line shifts of the 39K±(1/2 ± 1) / 2 central NMR transitions in the paraelectric (P) and incommensurate (I) phases of K2SeO4. The main effect of the P-I phase transition on these tensors is the appearance of nonzero off-diagonal elements Vab and Vbc which reflects the destruction of mirror planes by frozen-in soft-mode displacements along the b axis. From the angular dependences of the 77Se line shifts the 77Se chemical-shift tensor has been determined in the paraelectric phase of K2SeO4. In contrast to the 39K quadrupole-coupling and chemical-shift tensors it remains unaffected on going through TI and changes only slightly at TC

Dynamical decoupling of a qubit with always-on control fields

We consider dynamical decoupling schemes in which the qubit is continuously manipulated by a control field at all times. Building on the theory of the Uhrig Dynamical Decoupling sequence (UDD) and its connections to Chebyshev polynomials, we derive a method of always-on control by expressing the UDD control field as a Fourier series. We then truncate this series and numerically optimize the series coefficients for decoupling, constructing the CAFE (Chebyshev and Fourier Expansion) sequence. This approach generates a bounded, continuous control field. We simulate the decoupling effectiveness of our sequence vs. a continuous version of UDD for a qubit coupled to fully-quantum and semi-classical dephasing baths and find comparable performance. We derive filter functions for continuous-control decoupling sequences, and we assess how robust such sequences are to noise on control fields. The methods we employ provide a variety of tools to analyze continuous-control dynamical decoupling sequences.Comment: 22 pages, 10 figure

Distorted opportunities on the labor market for trainees. Studies on the discrimination against foreign and/or female adolescents looking for vocational training positions in Switzerland

On the basis of the well substantiated postulate of systematic inequality during the obligatory time of schooling, consequences for subsequent vocational training are to be expected in two sectors, in particular: on the one hand, the forced cooling down of the vocational aspirations of the affected adolescents themselves; on the other hand, an aggravated entry into the market for trainee poisitions. A study carried out among 1038 adolescents documents these consequences among different groups of students. Furthermore, differences in symbolic credits and between the available social resources are shown to have a strong impact on the structure of the transition into vocational lif

Chancenungleichheit bei der Lehrstellensuche: Der Einfluss von Schule, Herkunft und Geschlecht

No abstract available

Aes Grave. Das Schwergeld Roms u. Mittelitaliens, etc

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