Fidelity and coherence measures from interference

By utilizing single particle interferometry, the fidelity or coherence of a pair of quantum states is identified with their capacity for interference. We consider processes acting on the internal degree of freedom (e.g., spin or polarization) of the interfering particle, preparing it in states ρA or ρB in the respective path of the interferometer. The maximal visibility depends on the choice of interferometer, as well as the locality or nonlocality of the preparations, but otherwise depends only on the states ρA and ρB and not the individual preparation processes themselves. This allows us to define interferometric measures which probe locality and correlation properties of spatially or temporally separated processes, and can be used to differentiate between processes that cannot be distinguished by direct process tomography using only the internal state of the particle

Hawking Radiation as Tunneling

We present a short and direct derivation of Hawking radiation as a tunneling process, based on particles in a dynamical geometry. The imaginary part of the action for the classically forbidden process is related to the Boltzmann factor for emission at the Hawking temperature. Because the derivation respects conservation laws, the exact spectrum is not precisely thermal. We compare and contrast the problem of spontaneous emission of charged particles from a charged conductor.Comment: LaTeX, 10 pages; v2. journal version, added section on relation of black hole radiation to electric charge emission from a charged conducting sphere; v3. restored cut referenc

Identifying hybridizing taxa within the Daphnia longispina species complex: a comparison of genetic methods and phenotypic approaches

Daphnia galeata Sars, D. longispina O. F. Muller and D. cucullata Sars (Crustacea: Cladocera) are closely related species which often produce interspecific hybrids in natural populations. Several marker systems are available for taxon determination in this hybridizing complex, but their performance and reliability has not been systematically assessed. We compared results from identifications by three molecular methods. More than 1,200 individuals from 10 localities in the Czech Republic were identified as parental species or hybrids by allozyme electrophoresis and the analysis of the restriction fragment length polymorphism of the internal transcribed spacer (ITS-RFLP); over 440 of them were additionally analyzed and identified by 12 microsatellite loci. Identification by microsatellite markers corresponded well with allozyme analyses. However, consistent discrepancies between ITS-RFLP and other markers were observed in two out of 10 studied localities. Although some marker discrepancies may have been caused by occasional recent introgression, consistent deviations between ITS-RFLP and other markers suggest a long-term maintenance of introgressed alleles. These results warn against its use as a sole identification method in field studies. Additionally, we quantitatively evaluated the discriminatory power of geometric morphometric (elliptic Fourier) analysis of body shapes based on photos of over 1,300 individuals pre-classified by allozyme markers. Furthermore, a randomly selected subset of 240 individuals was independently determined from photos by several experts. Despite a tendency for morphological divergence among parental Daphnia species, some taxa (especially D. galeata, D. longispina, and their hybrids) substantially overlapped in their body shapes. This was reflected in different determination success for particular species and hybrids in discriminant analysis based on shape data as well as from photograph

Statistical Model Predictions for p+p and Pb+Pb Collisions at LHC

Particle production in p+p and central Pb+Pb collisions at LHC is discussed in the context of the statistical thermal model. For heavy-ion collisions, predictions of various particle ratios are presented. The sensitivity of several ratios on the temperature and the baryon chemical potential is studied in detail, and some of them, which are particularly appropriate to determine the chemical freeze-out point experimentally, are indicated. Considering elementary interactions on the other hand, we focus on strangeness production and its possible suppression. Extrapolating the thermal parameters to LHC energy, we present predictions of the statistical model for particle yields in p+p collisions. We quantify the strangeness suppression by the correlation volume parameter and discuss its influence on particle production. We propose observables that can provide deeper insight into the mechanism of strangeness production and suppression at LHC.Comment: 7 pages, 5 figures, conference contribution to "International school of nuclear physics", Erice, Sicily, 16 - 24 September 2008; Progress in Particle and Nuclear Physics, 2009, in pres

Statistical Model Predictions for Pb-Pb Collisions at LHC

The systematics of Statistical Model parameters extracted from heavy-ion collisions at lower energies are exploited to extrapolate in the LHC regime. Predictions of various particle ratios are presented and particle production in central Pb-Pb collisions at LHC is discussed in the context of the Statistical Model. The sensitivity of several ratios on the temperature and the baryon chemical potential is studied in detail, and some of them, which are particularly appropriate to determine the chemical freeze-out point experimentally, are indicated. The impact of feed-down contributions from resonances, especially to light hadrons, is illustrated.Comment: 5 pages, 2 figures, 1 table, SQM 2006 conference proceedings, accepted for publication in J. Phys.

Transmitting qudits through larger quantum channels

We address the problem of transmitting states belonging to finite dimensional Hilbert space through a quantum channel associated with a larger (even infinite dimensional) Hilbert space.Comment: 5 pages, ReVTeX, minor changes, to appear in J. Phys.

Statistical Model Predictions for Particle Ratios at sqrt(s_NN) = 5.5 TeV

Particle production in central Pb-Pb collisions at LHC is discussed in the context of the Statistical Model. Predictions of various particle ratios are presented with the corresponding choice of model parameters made according to the systematics extracted from heavy-ion collisions at lower energies. The sensitivity of several ratios on the temperature and the baryon chemical potential is studied in detail, and some of them, which are particularly appropriate to determine the chemical freeze-out point experimentally, are indicated. We show that the anti-p / p ratio is most suitable to determine the baryon chemical potential while the Omega / K and Omega / pi ratios are best to determine the temperature at chemical freeze-out.Comment: Submitted to Phys. Rev. C, 7 pages, 4 figure

Color-coded global topographic map of Mars

A Digital Terrain Model (DTM) was derived with both Mercator and Sinusoidal Equal-area projections from the global topographic map of Mars at a scale of 1:15 million and a contour interval of 1 km. Elevations on the map are referred to the Mars topographic datum that is defined by the gravity field at a 6.1-millibar pressure surface with respect to the center of mass of Mars. The DTM has a resolution at the equator of 1/59.226 degrees (exactly 1 km) per pixel. By using the DTM, color-coded global maps of Mars' topography were generated in both the Mercator projection and the Sinusoidal Equal-Area projection. On both maps, colors indicate 1 km increments of height. From the equal-are dataset, the positive and negative elevation distributions are calculated to be 67 and 33 percent, respectively