Calendar for Summer 2016

Talks take place on Wednesdays throughout the summer in 340 West Hall. Lunch will be provided at 11:45 and the presentations will be from 12:10 to 1:00pm.

  • May 18
  • The Origin of Mass: The Higgs Boson and Beyond
    Prof. Junjie Zhu, Physics
    Show Abstract
    Understanding the origin of mass of all fundamental particles is one of the key goals of the Large Hadron Collider program at CERN. I will explain major questions in particle physics, the Higgs mechanism, and current and future studies with the Higgs boson at ATLAS. In addition, I will also mention the detector, electronics, and computing research that we are doing here at Michigan.

    Submit Feedback
    Download Slides
  • May 25
  • Observational Cosmology with the Atacama Cosmology Telescope
    Kevin Coughlin, Physics, Advisor: Jeff McMahon
    Show Abstract
    The Cosmic Microwave Background (CMB) is one of the cleanest probes into the physics of the early universe. New technologies are continuously needed to improve measurements and further constrain cosmology. In this talk, I will give an overview of the goals and tools in observational cosmology, followed by an in-depth discussion on ground-based CMB observations, specifically of the Atacama Cosmology Telescope, and what work was done here at Michigan to make it a more powerful experiment.

    Submit Feedback
    Download Slides
  • June 1
  • Probing Photosynthetic Energy Transfer Using Ultrafast Multidimensional Spectroscopy
    Veronica Policht, Applied Physics, Advisor: Jennifer Ogilvie
    Show Abstract
    Photosynthesis, the process by which energy absorbed from sunlight is converted into sugars, is a topic of intense study across multiple disciplines. In recent decades, advances in laser technology have enabled the study of the ultrafast reactions that take place in the initial steps of photosynthesis. This talk will discuss current questions in photosynthesis research and will cover two-dimensional electronic spectroscopy (2DES), an ultrafast multidimensional spectroscopy technique which has helped advance our understanding of these reactions in recent years. Finally, I will present some 2D data of photosynthetic reaction centers and discuss our ongoing analysis.

    Submit Feedback
  • June 8
  • Coherent Nonlinear Spectroscopy of Semiconductor Quantum Dots
    Cameron Nelson, EECS, Advisor: Duncan Steel
    Show Abstract
    In this talk I will describe the basics of third order coherent nonlinear spectroscopy measurements in the frequency domain. The application for this measurement will be in understanding the dynamics of charge carriers excited into semiconductor quantum dots, a solid state system that has similar optical properties to atoms. I will show some of the uses for quantum dots, such as in quantum information devices, light emitters and optical modulators/switches and why our measurements are relevant to these applications. Finally, I will describe some of our recent work on InGaN/GaN quantum dots.

    Submit Feedback
    Download Slides
  • June 15
  • Examining Tatooine: Atmospheric Models of Neptune-Like Circumbinary Planets
    Erin May, Astronomy, Advisor: Emily Rauscher
    Show Abstract
    Circumbinary planets experience a time varying irradiation pattern as they orbit their two host stars. In this presentation, I will discuss the first detailed study of the atmospheric effects of this irradiation pattern on known and hypothetical gaseous circumbinary planets. Using both a one-dimensional Energy-Balance Model and a three-dimensional General Circulation Model, we explore the effects of the varying irradiation on atmospheric temperature and wind patterns in order to identify any atmospheric differences as a result of the binary host stars. We conclude that gaseous circumbinary planets can be treated as their equivalent single-star case in future atmospheric modeling efforts.

    Submit Feedback
    Download Slides
  • June 22
  • Planar Cell Chirality: How Cells Know Right From Left
    Jeremy Hadidjojo, Physics, Advisor: David Lubensky
    Show Abstract
    In developmental biology we discover how collections of cells assemble into complex organs. Similar to self-assembly, this process is driven by a cleverly-designed interaction between cells and is largely independent of external forces. A recurring theme is 'Planar Cell Polarity' (PCP), where the interaction is such that within cells different proteins segregate into different ends of the cell, and between cells these proteins want to align with each other. Similar to Ising magnets, this breaks rotational symmetry and gives tissue a preferred direction - allowing it, for example, to elongate or shrink in a certain direction. More interestingly, some cells can also break chiral symmetry this way. Dubbed 'Planar Cell Chirality' (PCP), this allows tissues to tell left from right and make yet more complex shapes. In this presentation, I will start by introducing PCP and how to model it. As we turn into PCC, we will see various ways chiral symmetry can be spontaneously broken, and how it is related to PCP. In particular, I will argue that PCC can be achieved simply by tuning the parameters of an existing PCP machinery.

    Submit Feedback
  • June 29
  • Acoustic Source Localization
    Brian Worthmann, Applied Physics, Advisor: David Dowling
    Show Abstract
    In our everyday lives, sound is typically used for communication and entertainment. However, clever use of physics and math can use that same sound to determine information about the environment in which it propagates. In this talk, we'll discuss various physics-based signal processing techniques for acoustic source localization, including spectrograms, beamforming, and matched field processing.

    Submit Feedback
    Download Slides
  • July 6
  • Quantum Network: Interfacing Quantum Dots with Cavity-Enhanced SPDC Photons
    Uttam Paudel, Physics, Advisor: Duncan Steel
    Show Abstract
    Since the proposal of Shor's algorithm, the field of quantum information science has garnered much interest from both the fundamental physics and applied communities. Various protocols, such as quantum computing, quantum cryptography, quantum teleportation, have been proposed that exploit quantum coherence and entanglement for information processing, which could be superior to the existing classical systems. Quantum networks are an integral part of many such protocols where information is transferred between nodes using optical interactions between a stationary qubit, such as quantum dots, and a flying qubit (single photons). In this talk I will discuss our ongoing effort to create the building blocks for a quantum network with quantum dots and entangled photon sources using a cavity-enhanced spontaneous parametric down-conversion source (SPDC), both of which can be engineered to ultimately allow distribution of entanglement between disparate quantum nodes.

    Submit Feedback
  • July 13
  • Early Alumnae of Michigan Physics
    Julia Bourg, Biophysics, Advisor: Sarah Veatch
    Show Abstract
    Three years ago, the Society for Women in Physics (SWIP) started searching for the names of first alumnae of the Physics Department. The SWIP history committee has since documented and researched the lives of most of the women to earn Physics degrees at Michigan in the early to mid-1900s. In this talk, Julia will share stories on various professors and alumnae, including the first Chinese women to earn degrees in Physics and a nun who worked on the Manhattan project!

    Submit Feedback
  • July 20
  • Surface Phase Stability and Intermixing on InAsSb Alloy Surfaces
    Evan Anderson, MSEG, Advisor: Joanna Millunchick
    Show Abstract
    InAsSb has the narrowest bandgap of any of the conventional III-V semiconductors: low enough for long wavelength infrared applications. Such devices are sensitive to point defects, which can be detrimental to performance. To control these defects, all aspects of synthesis must be considered, especially the atomic bonding at the surface. I use an ab initio statistical mechanics approach that combines density functional theory with a cluster expansion formalism to determine the stable surface reconstructions of Sb (As) on InAs (InSb) substrates. Scanning tunneling microscopy and reflection high energy electron diffraction confirm the calculated phase diagram. Additionally, depositing Sb on InAs causes an increase in the coverage of vacancies and islands in the As dimer rows. Based on these calculations and observations, I propose a new explanation for Sb-As intermixing in these materials.

    Submit Feedback
  • July 27
  • Probing the Dark Sector: Understanding the 95% of the Universe We Can't See
    Anthony Kremin, Physics, Advisors: August Evrard, David Gerdes, and Christopher Miller
    Show Abstract
    In the past several decades, it has become increasingly apparent that the matter we see around us is just a small portion of a much bigger whole. Through multiple independent techniques it has been shown that dark energy and dark matter constitute roughly 95% of all the energy in the Universe. I will briefly outline the history and characteristics of these two dark components before delving into current optical experiments aimed at unlocking their mysteries. The talk will then narrow into my research focus(es) of galaxy spectroscopy and the study of galaxy clusters. Lastly, I will discuss the future experiments that the University of Michigan is involved in and the impacts they should have.

    Submit Feedback
  • Aug 3
  • Black Holes: From billiard balls to strings, and everything in-between
    Anthony Charles, MCTP, Advisor: Finn Larsen
    Show Abstract
    Ever since their initial prediction, black holes have led to surprising new advances in physics. In this talk, I will document how our theoretical understanding of black holes has changed over time. In particular, I will focus on the puzzles and paradoxes that have led to new ideas in black hole physics. Lastly, I'll discuss ongoing efforts of research into quantum black holes, and why new ideas in string theory might hold the key to understanding black holes once and for all.

    Submit Feedback
    Download Slides
  • Aug 10
  • NOTE: This week has NO talk.
  • Aug 17
  • Probing the Secrets of Matter with Thermal Measurements in High Magnetic Fields Using Capacitative Thermometry
    Colin Tinsman, Physics, Advisor: Lu Li
    Show Abstract
    Thermal transport measurements are an important class of experiments in condensed matter physics. While only charged excitations such as electrons and holes participate in electrical transport, all types of excitations participate in the flow of heat. Recently, there has been a great deal of interest in measuring the thermal Hall Effect, the thermal transport analogue of the classical Hall Effect. The experiment involves making sensitive measurements of temperature in intense magnetic fields and low temperatures. Commonly used resistive thermometers are not suitable for the task; their resistance will change significantly in the presence of a strong magentic field at cryogenic temperatures. My work has been to create thermometers which do not have this issue, which work by measuring the temperature-sensitive dielectric constant of Strontium Titanate (SrTiO3). Using these, I have been able to measure the thermal Hall Effect in Bismuth metal, a material with a long history of discovery of new phenomena in condensed matter physics. I will also talk about how we are working to improve these thermometers, as well as measurements we would like to make with them on the topological Kondo insulator Samarium Hexaboride and the quantum magnet SrCu2(BO3)2.

    Submit Feedback
    Download Slides
  • Aug 24
  • Entropy, Phase Transition, and Shapes
    Chrisy Du, Physics, Advisor: Sharon Glotzer
    Show Abstract
    We encounter different materials in everyday life and these materials are held together using different forces from covalent bonds to the van der Waals force. People have been studying these different interactions for years, but recently, research has shown that by entropy alone ordered structures can arise from disorder. Here, we use a hard-particle system of different shapes (spheres, squares, tetrahedra, etc.) to study this phenomenon. We found that different shapes can order into different structures and sometimes a small perturbation in particle shape can change the ordered structure completely. We relate this behavior with other phase transitions in nature (i.e., vapor-water-ice) and try to understand its thermodynamic properties.

































Talks from Summer 2015 are here.

Maintained by Christopher Barnes (barnchri[at]umich[dot]edu)
PGSS at the University of Michigan, Summer, 2016