Hyperbolic Chaos of Turing Patterns

We consider time evolution of Turing patterns in an extended system governed by an equation of the Swift-Hohenberg type, where due to an external periodic parameter modulation long-wave and short-wave patterns with length scales related as 1:3 emerge in succession. We show theoretically and demonstrate numerically that the spatial phases of the patterns, being observed stroboscopically, are governed by an expanding circle map, so that the corresponding chaos of Turing patterns is hyperbolic, associated with a strange attractor of the Smale-Williams solenoid type. This chaos is shown to be robust with respect to variations of parameters and boundary conditions.Comment: 4 pages, 4 figure

Two-particle correlations in azimuthal angle and pseudorapidity in inelastic p + p interactions at the CERN Super Proton Synchrotron

Results on two-particle ΔηΔϕ correlations in inelastic p + p interactions at 20, 31, 40, 80, and 158 GeV/c are presented. The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The data show structures which can be attributed mainly to effects of resonance decays, momentum conservation, and quantum statistics. The results are compared with the Epos and UrQMD models.ISSN:1434-6044ISSN:1434-605

Stimulated Emission up to 2.75 µm from HgCdTe/CdHgTe QW Structure at Room Temperature

Heterostructures with thin Hg(Cd)Te/CdHgTe quantum wells (QWs) are attractive for the development of mid-infrared interband lasers. Of particular interest are room-temperature operating emitters for the short-wavelength infrared range (SWIR, typically defined as 1.7–3 μm). In this work, we report on the observation of stimulated emission (SE) in the 2.65–2.75 µm wavelength range at room temperature in an optically pumped HgCdTe QW laser heterostructure. We study a series of three samples with lengths ranging from 2.5 to 7 mm and discuss the effects related to the non-uniformity of the excitation beam profile. SE threshold intensity and the magnitude of pump-induced carrier heating are found to be effectively dependent on the chip size, which should be accounted for in possible designs of HgCdTe-based optical converters. We also pay attention to the problem of active medium engineering in order to push the SE wavelength towards the 3–5 µm atmospheric window and to lower the SE threshold