The lateral distributions of charged particles of energy greater than 0.3 E sub crit in electron-photon cascades in lead and air

In recent investigations, both theoretical and experimental, the agreement between cascade theory and experimental data is pointed out. The radial distributions obtained from the Monte Carlo simulation are compared ith the results of the analytical theory for all particles in cascades. The data on the mean radius of electron lateral distribution in air are compared with those in lead

Modelling and optimization of photon pair sources based on spontaneous parametric down-conversion

We address the problem of efficient modelling of photon pairs generated in spontaneous parametric down-conversion and coupled into single-mode fibers. It is shown that when the range of relevant transverse wave vectors is restricted by the pump and fiber modes, the computational complexity can be reduced substantially with the help of the paraxial approximation, while retaining the full spectral characteristics of the source. This approach can serve as a basis for efficient numerical calculations, or can be combined with analytically tractable approximations of the phase matching function. We introduce here a cosine-gaussian approximation of the phase matching function which works for a broader range of parameters than the gaussian model used previously. The developed modelling tools are used to evaluate characteristics of the photon pair sources such as the pair production rate and the spectral purity quantifying frequency correlations. Strategies to generate spectrally uncorrelated photons, necessary in multiphoton interference experiments, are analyzed with respect to trade-offs between parameters of the source

The Moho as a magnetic boundary

Magnetic data are presented for mantle derived rocks: peridtites from St. Pauls rocks, dunite xenoliths from the kaupulehu flow in Hawaii, as well as peridolite, dunite and eclogite xenoliths from Roberts Victor, Dutoitspan, Kilbourne Hole, and San Carlos diatremes. The rocks are paramagnetic or very weakly ferromagnetic at room temperature. Saturation magnetization values range from 0.013 emu/gm to less than 0.001 emu/gm. A review of pertinent literature dealing with analysis of the minerals in mantle xenoliths provides evidence that metals and primary Fe3O4 are absent, and that complex CR, Mg, Al, and Fe spinels dominate the oxide mineralogy. All of the available evidence supports the magnetic results, indicating that the seismic MOHO is a magnetic boundary

Satellite and surface geophysical expression of anomalous crustal structure in Kentucky and Tennessee

An equivalent layer magnetization model is discussed. Inversion of long wavelength satellite magnetic anomaly data indicates a very magnetic source region centered in south central Kentucky. Refraction profiles suggest that the source of the gravity anomaly is a large mass of rock occupying much of the crustal thickness. The outline of the source delineated by gravity contours is also discernible in aeromagnetic anomaly patterns. The mafic plutonic complex, and several lines of evidence are consistent with a rift association. The body is, however, clearly related to the inferred position of the Grenville Front. It is bounded on the north by the fault zones of the 38th Parallel Lineament. It is suggested that such magnetization levels are achieved with magnetic mineralogies produced by normal oxidation and metamorphic processes and enhanced by viscous build-up, especially in mafic rocks of alkaline character

The visibility study of S-T+_+ Landau-Zener-St\"uckelberg oscillations without applied initialization

Probabilities deduced from quantum information studies are usually based on averaging many identical experiments separated by an initialization step. Such initialization steps become experimentally more challenging to implement as the complexity of quantum circuits increases. To better understand the consequences of imperfect initialization on the deduced probabilities, we study the effect of not initializing the system between measurements. For this we utilize Landau-Zener-St\"uckelberg oscillations in a double quantum dot circuit. Experimental results are successfully compared to theoretical simulations.Comment: 8 pages, 5 figure

Enhanced charge detection of spin qubit readout via an intermediate state

We employ an intermediate excited charge state of a lateral quantum dot device to increase the charge detection contrast during the qubit state readout procedure, allowing us to increase the visibility of coherent qubit oscillations. This approach amplifies the coherent oscillation magnitude but has no effect on the detector noise resulting in an increase in the signal to noise ratio. In this letter we apply this scheme to demonstrate a significant enhancement of the fringe contrast of coherent Landau-Zener-Stuckleberg oscillations between singlet S and triplet T+ two-spin states.Comment: 3 pages, 3 figure

Prospective Minority Students\u27 Perceptions of Application Packets for Professional Psychology Programs: A Qualitative Study

This article reports the results of a qualitative study designed to determine issues salient in Black and Hispanic American students\u27 review and evaluation of program-application packets in professional psychology. The study served as an extension to the Yoshida et al. (1989) quantitative investigation. Students interested in pursuing doctoral studies in counseling or school psychology (N = 22) served as the sample. The qualitative methodology incorporated a think-aloud procedure and semistructured interviews. A theme analysis of transcribed interviews identified both major and minor themes central to participants\u27 evaluation of the packets. Major themes included financial aid, program requirements and course descriptions, demography of the student body, and the quality and clarity of application material. Specific suggestions on developing an application packet to send to inquiring prospective students are put forth. It is recommended that such a packet could serve as a cost-effective minority-recruitment strategy

Optical readout of charge and spin in a self-assembled quantum dot in a strong magnetic field

We present a theory and experiment demonstrating optical readout of charge and spin in a single InAs/GaAs self-assembled quantum dot. By applying a magnetic field we create the filling factor 2 quantum Hall singlet phase of the charged exciton. Increasing or decreasing the magnetic field leads to electronic spin-flip transitions and increasing spin polarization. The increasing total spin of electrons appears as a manifold of closely spaced emission lines, while spin flips appear as discontinuities of emission lines. The number of multiplets and discontinuities measures the number of carriers and their spin. We present a complete analysis of the emission spectrum of a single quantum dot with N=4 electrons and a single hole, calculated and measured in magnetic fields up to 23 Tesla.Comment: 9 pages, 3 figures, submitted to Europhysics Letter

Experimental demonstration of entanglement-enhanced classical communication over a quantum channel with correlated noise

We present an experiment demonstrating entanglement-enhanced classical communication capacity of a quantum channel with correlated noise. The channel is modelled by a fiber optic link exhibiting random birefringence that fluctuates on a time scale much longer than the temporal separation between consecutive uses of the channel. In this setting, introducing entanglement between two photons travelling down the fiber allows one to encode reliably up to one bit of information into their joint polarization degree of freedom. When no quantum correlations between two separate uses of the channel are allowed, this capacity is reduced by a factor of more than three. We demonstrated this effect using a fiber-coupled source of entagled photon pairs based on spontaneous parametric down-conversion, and a linear-optics Bell state measurement.Comment: 4 pages, 2 figures, REVTe

Density matrix of a single photon produced in parametric down conversion derived

We introduce an effective numerical method of density matrix determination of fiber coupled single photon generated in process of spontaneous parametric down conversion in type I non-collinear configuration. The presented theory has been successfully applied in case of source exploited in Phys. Rev. Lett. 99, 123601 (2007) to demonstrate the experimental characterization of spectral state of single photon