Araneae and Opiliones From \u3ci\u3eTypha\u3c/i\u3e Spp. And \u3ci\u3ePhragmites Australis\u3c/i\u3e Stands of Green Bay, Lake Michigan, and an Exotic Spider Species Newly Reported From the U.S. Great Lakes Region

Invertebrates were sampled using pan traps in three paired sets of Typha spp. (cattail) and Phragmites australis (giant reed grass) habitats in Lake Michigan’s Green Bay in June and September 2002. The collection included 34 harvestmen belonging to one species (found at all three sites), and 180 spiders belonging to 25 species in eight families. The two habitats yielded similar numbers of spider taxa, and 16 species were restricted to one of the two habitats. Between 10 and 15 species were found at each site, and only five spider species were collected at all three sites. Four species appear to be new records for the state of Wisconsin, including the linyphiid spiders Hypomma marxii (Keyserling) and Sitalcus ruralis Bishop & Crosby, and the salticid Synageles noxiosus (Hentz). Of particular interest is the first report from the U.S. Great Lakes region of the clubionid spider Clubiona pallidula (Clerck), a species introduced from Eurasia

Identification and Control of Electron-Nuclear Spin Defects in Diamond

We experimentally demonstrate an approach to scale up quantum devices by harnessing spin defects in the environment of a quantum probe. We follow this approach to identify, locate, and control two electron-nuclear spin defects in the environment of a single nitrogen-vacancy center in diamond. By performing spectroscopy at various orientations of the magnetic field, we extract the unknown parameters of the hyperfine and dipolar interaction tensors, which we use to locate the two spin defects and design control sequences to initialize, manipulate, and readout their quantum state. Finally, we create quantum coherence among the three electron spins, paving the way for the creation of genuine tripartite entanglement. This approach will be useful in assembling multispin quantum registers for applications in quantum sensing and quantum information processing

The Phonetics and Phonology of the Polish Calling Melodies

Two calling melodies of Polish were investigated, the routine call, used to call someone for an everyday reason, and the urgent call, which conveys disapproval of the addressee’s actions. A Discourse Completion Task was used to elicit the two melodies from speakers of Polish using twelve names from one to four syllables long; there were three names per syllable count, and speakers produced three tokens of each name with each melody. The results, based on eleven speakers, show that the routine calling melody consists of a low F0 stretch followed by a rise-fall-rise; the urgent calling melody, on the other hand, is a simple rise-fall. Systematic differences were found in the scaling and alignment of tonal targets: the routine call showed late alignment of the accentual pitch peak and in most instances lower scaling of targets. The accented vowel was also affected, being overall louder in the urgent call. Based on the data and comparisons with other Polish melodies, we analyse the routine call as LH* !H-H% and the urgent call as H* L-L%. We discuss the results and our analysis in light of recent findings on calling melodies in other languages, and explore their repercussions for intonational phonology and the modelling of intonation

An acoustic analog to the dynamical Casimir effect in a Bose-Einstein condensate

We have realized an acoustic analog to the Dynamical Casimir effect. The density of a trapped Bose-Einstein condensate is modulated by changing the trap stiffness. We observe the creation of correlated excitations with equal and opposite momenta, and show that for a well defined modulation frequency, the frequency of the excitations is half that of the trap modulation frequency.Comment: Includes supplemental informatio

Tunable source of correlated atom beams

We use a one-dimensional optical lattice to modify the dispersion relation of atomic matter waves. Four-wave mixing in this situation produces atom pairs in two well defined beams. We show that these beams present a narrow momentum correlation, that their momenta are precisely tunable, and that this pair source can be operated both in the regime of low mode occupancy and of high mode occupancy

Spontaneous Four-Wave Mixing of de Broglie Waves: Beyond Optics

We investigate the atom-optical analog of degenerate four-wave mixing of photons by colliding two Bose-Einstein condensates (BECs) of metastable helium and measuring the resulting momentum distribution of the scattered atoms with a time and space resolved detector. For the case of photons, phase matching conditions completely define the final state of the system, and in the case of two colliding BECs, simple analogy implies a spherical momentum distribution of scattered atoms. We find, however, that the final momenta of the scattered atoms instead lie on an ellipsoid whose radii are smaller than the initial collision momentum. Numerical and analytical calculations agree well with the measurements, and reveal the interplay between many-body effects, mean-field interaction, and the anisotropy of the source condensate

Anisotropy in s-wave Bose-Einstein condensate collisions and its relationship to superradiance

We report the experimental realization of a single-species atomic four-wave mixing process with BEC collisions for which the angular distribution of scattered atom pairs is not isotropic, despite the collisions being in the $s$-wave regime. Theoretical analysis indicates that this anomalous behavior can be explained by the anisotropic nature of the gain in the medium. There are two competing anisotropic processes: classical trajectory deflections due to the mean-field potential, and Bose enhanced scattering which bears similarity to super-radiance. We analyse the relative importance of these processes in the dynamical buildup of the anisotropic density distribution of scattered atoms, and compare to optically pumped super-radiance.Comment: 13 pages, 10 figures, added a fuller discussion of timescales, otherwise some minor changes in the text and the formatting of Figures 5-

Sub-Poissonian number differences in four-wave mixing of matter waves

We demonstrate sub-Poissonian number differences in four-wave mixing of Bose-Einstein condensates of metastable helium. The collision between two Bose-Einstein condensates produces a scattering halo populated by pairs of atoms of opposing velocities, which we divide into several symmetric zones. We show that the atom number difference for opposing zones has sub-Poissonian noise fluctuations whereas that of nonopposing zones is well described by shot noise. The atom pairs produced in a dual number state are well adapted to sub shot-noise interferometry and studies of Einstein-Podolsky-Rosen-type nonlocality tests.Comment: 4 pages, 3 figure