Department of Physics

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Colloquia & Seminars, Spring 2019

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Emergent phenomena: from starlings to spin liquids

Speaker: Dr. Rebecca Flint
Date: Friday, April 19, 2019
Time: 4pm
Room: 205 Currens Hall

Abstract:  Some of the most exciting problems and phenomena in physics today come not from the fundamental interactions of a few particles, but the novel collective behavior of many particles. While we understand the behavior of a single electron extremely well, the behavior of 1023 electrons is more readily described by collective modes of all of the electrons, which themselves behave like novel types of fundamental particles. Spin liquids are one such emergent phase of matter; at high temperatures, these phases can be described as an independent magnet sitting at each site of a lattice, but at low temperatures they develop strong correlations, leading to exotic critical collective behavior. In this talk, we will explore several examples of critical collective behavior, from starlings to the critical point of water to spin liquids.

About the speaker: Dr. Rebecca Flint is an Assistant Professor at the Department of Physics & Astronomy, Iowa State University. She is a theoretical condensed matter physicist studying strongly correlated electronic systems like spin liquids and heavy fermion materials.

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2019 Morrow Lecture: A Case for Quantum Biology: Application of Quantum Mechanics to Biology

Speaker: Dr. Kishor Kapale
Date: Friday, April 12, 2019
Time: 4pm
Room: 109 Morgan Hall

Nobel prize winner

About the speaker: Dr. Kapale  is a theoretical physicist whose research focuses on quantum optics, atomic optics, quantum information theory and applied quantum physics. Dr. Kapale did his MS in Physics from Indian Institute of Technology, Bombay (now Mumbai). He did his PhD work at Texas A&M University in the area of theoretical quantum optics. After spending a semester at Princeton University he moved to Jet Propulsion Laboratory, California Institute of Technology as a National Research Council Research Associate and NASA Postdoctoral Fellow. He joined the WIU Department of Physics in Fall of 2007.

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Evidence for Shocked Gas Traced by Hydroxyl Masers in Early High-Mass Star-Forming Regions

Speaker: Emma Clark
Date: Monday, April 7, 2019
Time: 3pm
Room: 205 Currens Hall

Abstract:  High-mass stars form by gravitational collapse of massive molecular clouds. Observations have shown that young high-mass stellar objects drive molecular outflows and ionized jets. In particular, Rosero et al. (2016) conducted high sensitivity VLA observations of a sample of 58 high-mass star-forming regions and reported detection of 70 radio continuum sources associated with dust clumps. A follow up analysis shows that around half of the sample of the radio sources are likely ionized jets. If so, evidence for shocks related to the expansion of the ionized jets should be detectable. We present a search for shocked gas traced by 1720 MHz hydroxyl masers toward the sample of Rosero et al. (2016). The hydroxyl data are from the VLA THOR survey. We report three regions with clear detection of 1720 MHz OH masers and many tentative detections. We studied these regions further by searching for 1612 MHz, 1665 MHz, and 1667 MHz hydroxyl masers at the galactic coordinates of the detections. We analyze the detections based on the radio continuum properties of the regions, and discuss a follow up observing proposal that was recently submitted to obtain higher spectral resolution images with the Very Large Array.

About the speaker:  Emma Clark is a Physics senior undergraduate student.

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Variation of the Refractive Index of Barium Bismuth Borate Glasses

Speaker: John Turton
Date: Monday, April 7, 2019
Time: 3pm
Room: 205 Currens Hall

Abstract:  Glasses play a very important role in our technological society. They are used in a wide variety of applications from windows to camera lenses, and glass containers to lasers. Refractive index is a fundamental optical property of any glass that is crucial in determining its potential for applications in optical devices. In this study, we report the variation of the refractive index of barium bismuth borate glasses with glass composition. Barium Carbonate, Bismuth Oxide, and Boric Acid are the starting materials that we used to prepare these glasses. We measured each chemical out and poured them into a crucible. We melted the samples in a furnace and the melt is then poured onto a brass plate and covered with another brass plate to bring down the temperature to form the glass. After the glass samples had cooled, we placed them in a second furnace to anneal the samples. The annealed glass samples are then polished to obtain smooth reflecting surfaces for the refractive index measurements. Refractive indices are measured using the Brewster angle method and the densities are determined using the Archimedes’ principle. Our glass samples show densities in the range 5.5-5.8 g/cm3and the refractive indices varied from 1.801 to 1.813. The refractive index is mostly constant. The higher value of the density and the refractive index is attributed to the presence of the heavy metal bismuth oxide in the glass composition.

About the speaker:  John Turton is a Physics senior undergraduate student.

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WIU Physics Department Lecture Series on Nobel Prizes

Generation of Intense Ultrashort Laser Pulses

Speaker: Dr. Pengqian Wang
Date: Friday, March 29, 2019
Time: 4pm
Room: 205 Currens Hall

Abstract:  "The Nobel Prize in Physics 2018 Arthur Ashkin, Gérard Mourou, Donna Strickland"
The Nobel Prize in Physics 2018 was awarded "for groundbreaking inventions in the field of laser physics" with one half to Arthur Ashkin "for the optical tweezers and their application to biological systems", the other half jointly to Gérard Mourou and Donna Strickland "for their method of generating high-intensity, ultra-short optical pulses."

About the speaker:  Dr. Pengqian Wang is a Professor of Physics, at Western Illinois University. His research aims interests are in experimental AMO physics, specifically in the following areas:

  • Dynamics of molecules in ultrafast intense laser fields.
  • Laser spectroscopy of atoms, molecules and clusters.
  • Electron impact dissociative ionization of molecules.
  • Nonlinear optical properties of materials.

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Dielectric Nanophotonics: the quest for lossless optical devices

Speaker: Dr. Uttam Mana
Date: Friday, February 8, 2019
Time: 4pm
Room: 205 Currens Hall

Abstract:  Nanoplasmonics is usually associated with noble metals that can confine light beyond the diffraction limit leading to unprecedent enhancement of the electric field with potentials to develop nanoscale optical interconnects, optical cloaking and super-resolution imaging, etc. However, overcoming the diffraction limit comes at a price - the high level of losses associated with free carriers in metals, limiting the efficiency of the optical devices. In this talk, I will discuss how resonant excitation of high-index dielectric nanostructures can pave an alternative route towards future nanophotonic devices because of their reduced dissipative losses and large resonant enhancement of both electric and magnetic near-fields. More specifically, I will focus on the discovery of the electrodynamic "anapole mode" (i.e. "without poles" in Greek) as a non-radiating source in high index dielectric materials. Subsequently, I will report the first experimental demonstration of electrodynamic anapoles in single silicon nanosphere (diameter ~ 160 nm) in our laboratory.

About the speaker:  Dr. Uttam Manna is an Assistant Professor of Physics, at Illinois State University. His research aims at understanding optical phenomena on the nanometer scale through a two-step process. First, confine light by classical means i.e. focus light using microscope objectives beyond the paraxial approximation. Then use the confined light as a probe to investigate resonance phenomena (electric and magnetic) in metal nanoparticle based structures.  They also study the interaction of light with other nanoscale systems such as quantum dots, rare earth elements, etc.

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