The diffusivity of Mn in CdTe, D(Mn), has been measured between 500 and 800 "C under saturated Cd and Te condaions. The variation of D(Mn) with Cd partial pressure was measured at 600 'C. Between 500 and 800 "Cfor saturated Te, and between 600 and 800 "C for saturated Cd D(Mn) = (1.12:9,12) x 1O3exp(-(2.76i0.18)eV/kT) cm2 s-', These results are consistent with those at 600 "C which show D(Mn) to increase with decreasing Cd partial pressure. It is argued that lhe observed features of D(Mn) can be best accounted for in terms of a V& diffusion mechanism.
State-of-the-art timing technique is used to determine the 'speed of light' in an upper level undergraduate laboratoryexperiment. In thisexperiment we use the wrrelated 51 1 keV photons from positron annihilation obtained from a IOOpCi Na-22 source. The photons were detected by two BaF2 scintillation detectors and, after careful time calibration of the entire counting system, the prompt coincidence peaks were each recorded as a function of the position of one of lhe detectors. As a result, the 'speed of tight' was determined to be 3.002(16) x 101ocms~i, which is very close to the defined value of 2.99192 x l0l0cms-'. This experiment demonstrates the utilization of various nuclear instrumentation and timing equipment.
In the canonical quantization of gravity in terms of the Ashtekar variables one uses paths in the 3-space to construct the quantum states. Usually, one restricts oneself to families of paths admitting only a finite number of isolated intersections. This assumption implies a limitation on the diffeomorphisms invariance of the introduced structures. In this work, using the previous results of Baez and Sawin, we extend the existing results to a theory admitting all the possible piecewise-smooth finite paths and loops. In particular, we (a) characterize the spectrum of the Ashtekar-Isham configuration space, (b) introduce spin-web states, a generalization of the spinnetwork states, (c) extend the diffeomorphism averaging to the spin-web states and derive a large class of diffeomorphism-invariant states and finally (d) extend the 3-geometry operators and the Hamiltonian operator. PACS number: 0460D J Lewandowski and T Thiemannconcerning diffeomorphism-invariant states of connections and associated diffeomorphisminvariant operators. Finally, in section 6 we apply the machinery of the previous sections to the operators that have proved to be elementary building blocks for the quantization of the gravitational field. The algebra of cylindrical functions on the space of connectionsThis section is divided into three parts. In the first part we recall the basic notions of cylindrical functions on the space of distributional connections and inductive limit structures, and review the results that one obtains if one labels cylindrical functions by piecewise analytic, finitely generated graphs. In the second part we review the construction, due to Baez and Sawin, of a new label set, called 'webs', which are appropriate for the case where the loops defining the Wilson functions are only piecewise smooth and may intersect each other an infinite number of times. Finally, in the third part we prove the master theorem on which the rest of this paper is based. PreliminariesIn the loop quantization of gravity as initiated by Ashtekar [1] and Jacobson, Rovelli and Smolin [2] and Gambini et al (see, e.g., [3] and references therein) through embedding general relativity into a Yang-Mills theory phase space and making use of Wilson loop variables as well as in a general framework for quantization of a diffeomorphism-invariant theory of connections with local degrees of freedom [4]
The effect of detuning on the probe absorption spectra of a two-level system in a squeezed vacuum is investigated, with and without the presence of a classically driven field. For strong squeezing, there is a threshold depending on the squeeze parameter M, which determines the positions and widths of the absorption peaks. For large detunings, the spectra exhibit a close resemblance to Fano spectra and for small detunings there is probe gain. We show that there are marked differences in the spectra between a minimum uncertainty squeezed vacuum (M = √ N (N + 1)) and a field state with the maximum classical two-photon correlations (M = N ). Observation of these features would confirm the essentially quantum-mechanical nature of the squeezed vacuum. † Also at
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