Winter 2017 Colloquium Series
Date: Thursday, January 12th, 2017
Speaker: Jameson Graef Rollins, Caltech
Title: LIGO: Our First Ears to the Cosmos
Abstract: In 2015 the Laser Interferometer Gravitational-wave Observatory, LIGO, detected gravitational waves for the first time ever, confirming their existence 100 years to the year after their initial prediction by Albert Einstein. While the significance of the initial detections can not be overstated, the physical phenomena that these devices now allow us to hear are the real prize. Already the sounds of colliding black holes from our initial detections has given us an unprecedented glimpse of gravity under extreme spacetime curvature. And surely more exotic discoveries are right around the corner. This talk will briefly describe the discoveries to date, and the instruments that made them possible, with an eye to how we expect the detectors to be made more sensitive in the coming years.
Date: Thursday, January 19th, 2017 : Colloquium cancelled due to winter weather issues.
Date: Thursday, January 26th, 2017
Speaker: Brian J. Smith, University of Oregon
Title: Color and Shape: The Quantum State of a Single Photon and its Manipulation
Abstract: Just over a century ago Max Planck introduced the quantized energy exchange between electromagnetic field modes in an optical cavity and the atoms comprising the walls at finite temperature to derive the spectral energy density of black body emission. Shortly thereafter, Einstein proposed that not only was the energy exchanged between the field and matter quantized, but that the radiation itself was quantized. He proposed that each light quantum, now called a photon, carries energy that is proportional to the frequency of the optical field mode. The frequency of a single photon is a central property that defines its physical state. Indeed, the full quantum state of a single photon is directly related to the electromagnetic field mode function that it occupies. Thus, we see that the central frequency of a single photon, often thought of as a defining property of a single light quantum, is not immutable, but can be modified just as the classical frequency of light can be manipulated. Here, we report the first experimental demonstration of deterministic spectral manipulation of single photons achieved by application of controlled spectral and temporal phases. These techniques lay the ground for future quantum wavelength- and time-division multiplexing applications and facilitate interfacing of different physical platforms where quantum information can be stored and manipulated.
Date: Thursday, February 2nd, 2017
Speaker: Sheila Dwyer, LIGO Hanford Observatory
Title: Opening the Gravitational Wave Universe: Extending the Reach of Gravitational Wave Detectors
Abstract: With the first direct detection of gravitational waves, the LIGO detectors have opened a new field of astrophysics, discovered a new class of massive stellar mass black holes, and enabled tests of general relativity. To make these discoveries, we built the most sensitive displacement meters yet, measuring displacements of one thousandth of a proton diameter over a 4 kilometer baseline. This talk will focus on the fundamental noise sources which limit the performance of gravitational wave detectors, and the possibilities for extending their reach. Squeezed states of light, cryogenic operation and new optical materials have the potential to dramatically increase the distances at which gravitational wave observations can be made. In a new and larger facility, LIGO style detectors could observe compact object binaries from the earliest periods of star formation, making complete surveys of an epoch difficult to observe with optical telescopes.
Date: Thursday, February 9th, 2017
Speaker: Barry Sanders, Institute for Quantum Science and Technology, Department of Physics and Astronomy, University of Calgary, Calgary, Canada
Title: A Stroll Through Quantum Walks
Abstract: The subject of quantum walks emerged from considerations of the ubiquitous random walks inherent in diffusion in physics and chemistry, randomized algorithms in computer science, and Wiener measures in mathematics. From its humble beginnings as a generalization of random walks, quantum walks have emerged into a large-scale theoretical and experimental research area that extends into a wide spectrum of areas including universal quantum computing, simulating topological phenomena, and modeling energy transport in certain biological molecular complexes. I begin with a primer on quantum walks and then cover current hot theoretical studies and experimental implementations of quantum walks.
Date: MONDAY, February 13th, 2017
Speaker: Evan Goetz, Ph.D., Max Planck Institute for Gravitational Physics, Germany
Title: A New Era of Gravitational Wave Astronomy
Abstract: With the first observations of gravitational waves by the Advanced LIGO detectors in September 2015, a new era of gravitational wave astronomy has begun. In this talk, I will discuss the first gravitational wave observations, describe the Advanced LIGO detectors and how they are calibrated, and summarize the analysis that uncovered the binary black hole coalescence. In addition, I will discuss other searches for continuous gravitational waves, a promising probe to study neutron star physics.
Date: Thursday, February 16th, 2017
Speaker: Susan Lehman, Claire Booth Luce Associate Professor of Physics at The College of Wooster in Wooster, Ohio
Title: Science on the Edge: Critical Phenomena in Granular Systems
Abstract: A granular system behaves in some ways like a liquid with an ability to flow, and in some ways like a solid with a stable fixed structure if undisturbed. A tiny stimulus to the pile most often results in only a small response, but the same small stimulus can also create an unpredictable and catastrophic collapse of the pile. These collapses occur both in natural settings, with hazards such as landslides and snow avalanches, and in industrial situations, where granular materials like sand or agricultural grains need to flow freely. We use a simple experimental system – a 3D conical pile of uniform beads – in order to model these real-world physical systems. We investigate the dynamic response of the pile by recording avalanches from the pile over the course of tens of thousands of bead drops. The resulting behavior is well-characterized by universal power laws and scaling functions, relating this work to the broader study of critical systems.
All of these results were obtained at The College of Wooster, a liberal arts college with a particular focus on mentored undergraduate research. As part of the talk, I will discuss how work at a liberal arts college differs from work at a large research university, and suggest ways to prepare for alternative academic careers.
Date: MONDAY, February 20th, 2017
Speaker: Robert L. Ward, Department of Quantum Science, RSPE, Australian National University
Title: Measuring Storms in Space-Time: Astronomy with Gravitational Radiation
Abstract: On September 14, 2015, the LIGO detectors recorded the first direct observation by humankind of gravitational waves — space-time distortions generated by objects with extreme gravity. These waves propagate over astrophysical distances and can be detected by the modulation imposed on the optical path of a suspended mirror laser interferometer. We now have a new form of radiation with which to study the Universe. The level of displacement sensitivity which enabled the first detections, less than 1 part in 10,000 of a proton diameter, mandates not only significant isolation from environmental noise, but also a readout scheme capable of measurement at this level. I will discuss gravitational waves and the technology developed to detect them, including the optical metrology techniques that enable the Advanced LIGO detectors to reach their extraordinary sensitivity and how we extract the signals necessary to control the interferometer. I will describe what we have observed so far and what we hope to learn about the universe with this new astronomical messenger
Date: Thursday, February 23rd, 2017
Speaker: Sarah Caudill, University of Wisconsin-Milwaukee
Title: From Gravitons to Electrons: the Discovery of GW151226
Abstract: LIGO’s detection of the first gravitational wave signal, GW150914, ushered in the era of gravitational wave astronomy with quite a bang, giving us a measurement of the heaviest stellar mass black holes to date and providing new stringent tests of general relativity. However, the detection of the second signal, GW151226, on December 26, 2015 was arguably just as exciting. I will describe the technology that allowed this signal to be detected just 70 seconds after arrival. Additionally, GW151226 spent nearly 55 cycles in LIGO’s sensitive band compared to only 10 cycles for GW150914. I will discuss the precise measurements of the compact binary parameters that were afforded by this longer signal. Finally, I will describe how these two gravitational wave detections inform our predictions for more discoveries in the near future.
Date: Monday, February 27th, 2017
Speaker: Laura Jeanty, Lawrence Berkeley National, Laboratory, Berkeley, CA
Title: Silicon, Straws, and SUSY: Searches for Supersymmetry featuring the ATLAS Inner Detector
Abstract: The keystone of the standard model of particle physics, the Higgs Boson, was discovered during the first run of the Large Hadron Collider (LHC). The LHC is halfway through its second run, with higher energy and higher intensity collisions providing a dataset ripe for discovery of physics beyond the standard model. Supersymmetry remains a promising theory for new physics accessible at the LHC. The inner tracking detector plays a crucial role in many searches for supersymmetry on the ATLAS experiment. In this talk, I will discuss the current status and outlook of supersymmetry searches by ATLAS, with a focus on the different ways in which the inner detector extends our sensitivity to new particles.
Date: Thursday, March 2nd, 2017
Speaker: Ben Farr, University of Chicago
Title: The First Four Months of Gravitational Wave Astronomy
Abstract: On September 14, 2015 LIGO made the first direct detection of gravitational waves, marking the true beginning of gravitational wave astronomy. I will present the methods behind the detection and characterization of LIGO’s binary black hole mergers, and what they have taught us about compact binaries thus far. I will focus in particular on the important astrophysical ramifications of these initial detections, and what we can be expected to learn in the near future from gravitational-wave astronomy.
Date: Thursday, March 9th, 2017
Speaker: Bill Atwood, UC Santa Cruz
Title: Exploring the Gamma Ray Universe: Fermi-LAT then, now, and the future
Abstract: The Gamma ray Large Area Space Telescope (GLAST) project began in 1992, a year after the launch of EGRET onboard the CGRO spacecraft. Capitalizing on advances in particle detector technology, the GLAST project developed an observatory that extends the discovery space of EGRET by over an order of magnitude. After its launch in 2008, GLAST was renamed Fermi-LAT and has performed an all-sky survey of the gamma ray universe ever since. This talk will present details of how the instrument was designed and how the design choices contributed to the success of the mission. The presentation will include highlights from the first 8+ years of the Fermi-LAT as well as its science potential going forward.