Physics Colloquium - Spring 2018

Speaker: Hosseini Mahdi, Purdue University

Abstract: Our ability to engineer quantum states of light and matter has significantly advanced over the past two decades fostering future quantum technologies including quantum optical communication, quantum sensing as well as quantum computation. The strong nonlinear light-atom interaction is the key to deterministic quantum state preparation and quantum photonic processing. One route to enhancing the usually weak nonlinear light-atom interactions is to approach the regime of cavity quantum electrodynamics (cQED) interaction by means of high quality optical resonators. I describe light-atom interactions in the weak and strong QED regime and show how such coherent interactions can be used to implement quantum storage, logic operations, and state engineering for optical information. Moreover, I present our ongoing effort at Purdue to realize quantum phenomena at the single photon level using chip-scale photonic systems.

Speaker: Joseph Wilkins, Computational Exposure Division, National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA

Abstract: The area burned by wildland fires (prescribed and wild) across the contiguous United States (U.S.) has expanded by nearly 50% and now averages 2 million hectares per year. Such fires are estimated to cause 8,000 deaths per year and are monetized as having a ~$450 billion impact to the U.S. economy. Air quality simulation models, like the Community Multiscale Air Quality (CMAQ) modeling system, are extensively used by environmental decision-makers to both examine the impact of air pollution on human health and devise strategies for reducing or mitigating exposure of humans to harmful levels of air pollution. With fires now occurring more frequently and burning more intensely, the exposure of humans to fine particulate matter (PM_2.5) and ozone (O₃) is projected to grow. Understanding how the contaminated plumes from these fire emissions move vertically through the atmosphere is important for estimating these exposures. Many air quality models rely on complex algorithms to determine transportation of air pollution, such as plume rise algorithms, which determine the vertical allocation of emissions. Recent findings have shown that by adding fires in CMAQ, it can be estimated that fires contributed 11% to mean PM_2.5 and less than 1% to mean O₃ concentrations during 2008-2012. During that same time frame the model indicated increases to number of “grid cell days” with PM_2.5 above 35 µg m^-3 by a factor of 4 and the number of grid cell days with maximum daily 8-hour average O₃ above 70 ppb by 14%. Furthermore, we explore current work looking to improve modeling efforts associated with fire emissions.

Speaker: YuCheng Shao, Tamkang University (Taiwan)

Abstract: The third-generation synchrotron radiation based spectroscopies such as X-ray diffraction (XRD) for lattice structure, X-ray absorption near edge structure (XANES) and X-ray linear dichroism (XLD) for electronic and orbital structures, X-ray magnetic circular dichroism (XMCD) for magnetic structure and X-ray emission spectroscopy (XES)/Resonant Inelastic X-ray Scattering (RIXS) for information about occupied states and their interactions are considerable and powerful techniques for investigations with complex coupling. Their excellent analytic capabilities are certainly exhibited in many strongly correlated systems like manganite thin films and Gadolinium (Gd)-based compounds.

Speaker: Nguyen Phuong Dang, University of Louisville, Department of Physics and Astronomy

Abstract: Although the Standard Model describes many experimental results with high accuracy, it still has weaknesses. The three electroweak bosons (W+/- and Z0) which were discovered experimentally in 1983 introduced mass terms to the equations of the Standard Model, and thus violated the gauge symmetries. A mechanism was proposed in 1964 by R. Brout, F. Englert and P. Higgs as the simplest solution to attribute mass not only to the W+/- and Z0 bosons but also to quarks and leptons while preserving the gauge symmetries of the Standard Model. This theoretical model, known as the "Englert-Brout-Higgs mechanism" or "Higgs mechanism", indicates the existence of one additional particle, the Higgs boson. The Large Hadron Collider (LHC) was built by the European Organization for Nuclear Research (CERN) with the major motivation of searching for the Higgs boson. Two multi-purpose detector systems, ATLAS (A Toroidal LHC ApparatuS) and CMS (Compact Muon Solenoid), were installed at the LHC to search independently for the Higgs boson and new phenomena beyond the Standard Model. This talk gives an overview of recent results in Higgs boson physics obtained with the ATLAS and CMS experiments, and prospects of future Higgs boson measurements at the LHC.