HIGH ENERGY ASTROPHYSICS Dafne GuettaWe study the physics and the redshift distribution of Gamma-Ray Bursts (GRBs) , bursts of 0.1-1 MeV photons lasting for few seconds. These are very energetic sources that can be used to probe the star formation rate. We study the high energy neutrino and gravitational wave emission from GRBsand other astrophysical sources like microquasars. We are interested in understanding what are the sources of ultra high energy cosmic rays and if hadrons are present in the jet of these sources.
HIGH TEMPERATURE SUPERCONDUCTIVITY (EXPERIMENTAL)Meni ShayThe main goal of the research is to check the hypothesis that there is a linear relation between the maximal transition temperature to the superconducting state and the magnetic coupling between neighboring unit cells in High Temperatures Superconductors. The tool that we use to probe the magnetic coupling is two-magnon Raman scattering. In addition the phase diagram of the samples is being studied by means of muon spin rotation, transport and magnetizations measurements. The samples are high quality single crystals, grown using an optical image zone furnace at the Technion. The crystals are unique and allow for several other different experimental investigations such as angle resolved photoemission spectroscopy, inelastic neutron scattering and more.
MICRO AND NANOELECTROMECHANICAL SYSTEMSYoav Linzon and Said MahajnaWe use synchronous imaging for the dynamic space-domain studies of vibration profiles in capacitively driven, thin n + doped polysilicon microbridges oscillating at rf frequencies. Fast and high-resolution actuation profile measurements of micromachined resonators are useful when significant device nonlinearities are present. For example, bridges under compressive stress near the critical Euler value often reveal complex dynamics stemming from a state close to the onset of buckling. This leads to enhanced sensitivity of the vibration modes to external conditions, such as pressure, temperatures, and chemical composition, the global behavior of which can be conveniently evaluated using synchronous imaging combined with spectral measurements. We performed an experimental study of high drive amplitude and ambient pressure effect on the resonant vibration profiles in electrically driven microbridges near critical buckling. Numerical analysis of electrostatically driven post-buckled microbridges supports the richness of complex vibration dynamics that are possible in such microelectromechanical devices. Micro-electromechanical systems (MEMS) and Nano-electromechanical systems (NEMS) are also used considered as leading candidates for sensitive detection of minute chemical concentrations.
QUANTUM CONTROLShimshon KallushQuantum Control (QC) is dedicated to driving objectives into a given goal in the microscopic world, which is governed by quantum mechanics. Our research interests within this area range from fundamental research to theoretically and experimentally applicative sides of the area. We deal with the basic questions of applicability of QC, like the sensitivity of a given control solution on the various parameters of the system. On the applicative branch of the research we explore numerical methods for computing numerically exact quantum dynamics under general condition, to serve as a tool for understading and predicting the ability to control quantum systems. We are also in tight connection with the experimental group of Prof. Phillip Gould in the University of Connecticut. The collaboration seeks for ways to apply quantum control methods to create ultra cold (micro Kelvin) molecules with the aid of light pulses that fit the typical dynamics of these species, i.e., in the nanosecond time scales.
SUPERCONDUCTIVITY (THEORETICAL)Jorge BergerWe study geometric effects on mesoscopic superconducting samples, mainly rings, by means of the Ginzbug-Landau model and generalizations of it. Special attention is given to thermal fluctuations,which are studied by means of appropriate Langevin functions.