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Spring 2017 Colloquium Series

Date: Thursday, June 1st, 2017
Speaker:   Tim Nelson, SLAC National Accelerator Laboratory

Title: Accelerating Dark Matter

Abstract:  The Standard Model of particle physics is a remarkably complete and self-consistent description of the fundamental physics of the universe.  However, the existence of dark matter, now known for nearly a century, has become compelling evidence that the Standard Model is not complete. The simplest extension of the Standard Model, to include so-called WIMPs that comprise the dark matter, has driven three decades of exploration that will soon reach fundamental limits. As a result, we have begun to consider other simple and well-motivated scenarios for dark matter, where the dark matter is part of a larger dark sector of particles and forces. The simplest and best motivated dark sector scenarios make clear predictions that are testable using the usual tools of particle physics, accelerators. In this talk, I will describe the search for dark sectors, including both dark matter and dark forces, at particle accelerators.

Host: Jim Brau

 

Date: TUESDAY, May 30th, 2017
Speaker:   Nobel-laureate physicist,  David J. Wineland, NIST, Boulder, Colorado

Title:  Single-atom Optical Clocks

Abstract:  With the availability of spectrally pure lasers and the ability to precisely measure optical frequencies, it appears the era of optical atomic clocks has begun.  In one clock project at NIST we have used a single trapped Al+ ion to make a clock based on an ultraviolet transition.  With single ions, uncertainties in systematic effects are smallest, reaching a fractional frequency error of Df/f0 = 8.0 x 10-18.  At this level, many interesting effects, including those due to special and general relativity, must be calibrated and corrected for.

Bio:  Winelands’ work as the founder of NIST’s ion storage group and as a member of the physics faculty of the University of Colorado at Boulder has led to advances in spectroscopy, atomic clocks and quantum      information. He shared the 2012 Nobel Prize in Physics with French physicist Serge Haroche “for groundbreaking experimental methods that enable measuring and manipulation of individual quantum systems.”

Host: Michael Raymer

 

Event:  David Wineland Public Talk
Date: TUESDAY, May 30th, 2017
Speaker:   David Wineland, NIST, Boulder, Colorado

Title:  Quantum Computers and Schrödinger’s Cat

Abstract:   What is quantum computing and what does it have to do with physicist Erwin Schrödinger’s famous quantum physics cat? In a free public lecture, Nobel-laureate physicist David Wineland will explore these topics and discuss how his research group at the National Institute of Standards and Technology became aware of their connection when carrying out experiments on individual atomic ions. Winelands’ work as the founder of NIST’s ion storage group and as a member of the physics faculty of the University of Colorado at Boulder has led to advances in spectroscopy, atomic clocks and quantum information. He shared the 2012 Nobel Prize in Physics with French physicist Serge Haroche “for groundbreaking experimental methods that enable measuring and manipulation of individual quantum systems.” The lecture is sponsored by the University of Oregon’s Office of the Vice President for Research and Innovation and the Department of Physics.

Host: Michael Raymer

 

Date: Thursday, May 25th, 2017
Speaker: Carlton M. Caves, Department of Physics & Astronomy, University of New Mexico

Title: Quantum-Limited Measurements: One Physicist’s Crooked Path from Quantum Optics to Quantum Information

Abstract: Quantum information science has changed our view of quantum mechanics. Originally viewed as a nag, whose uncertainty principles restrict what we can do, quantum mechanics is now seen as a liberator, allowing us to do things, such as secure key distribution and efficient computations, that could not be done in the realistic world of classical physics. Yet there is one area, that of quantum limits on high-precision measurements, where the two faces of quantum mechanics remain locked in battle. I will trace the history of quantum-limited measurements, from the use of nonclassical light to improve the phase sensitivity of an interferometer, to the modern perspective on the role of entanglement in improving measurement precision.

Bio: Carlton M. Caves is a Distinguished Professor in the Department of Physics and Astronomy at the University of New Mexico and Director of UNM’s Center for Quantum Information and Control. He received the PhD in Physics from the California Institute of Technology in 1979. He worked at Caltech as a postdoctoral Research Fellow through 1981 and as a Senior Research Fellow in Theoretical Physics from 1982 through 1987. From 1988 till 1992 he was Associate Professor of Electrical Engineering and Physics at the University of Southern California. He moved to to UNM as Professor of Physics and Astronomy in 1992. He is the author of over 140 scientific papers on topics in gravitation theory, quantum optics, nonlinear dynamics, and quantum information science. His present research is concentrated on quantum metrology and quantum information theory. He is a Fellow of the American Physical Society and the American Association for the Advancement of Science.

Host: Michael Raymer

 

 

Date: Thursday, May 18th, 2017
Speaker: Daniel McKinsey, UC Berkeley

Title: “Who Has Seen The WIMP? Neither You Nor I.”

Abstract: The LUX (Large Underground Xenon) experiment is designed for the
direct detection of dark matter particles via their collisions with xenon
nuclei. This two-phase xenon time-projection chamber has now completed operations deep underground on the 4850 foot level of the Sanford Underground Research Facility in Lead, South Dakota. Results will be presented from the 2013-2016 dark matter search data sets, as well from several novel detector calibrations using tritium, radioactive krypton, and monoenergetic neutrons from a deuterium-deuterium neutron generator. The LUX results are inconsistent with the low-mass WIMP signal interpretations of data from several recent direct detection experiments, and at 50  GeV c−2 exclude  WIMP-nucleon spin-independent cross sections above 1.1×10−46  cm2.  This talk will provide an overview of the LUX experiment, focusing on the most  recent science results, and describe the upcoming LUX-ZEPLIN experiment,  which is currently under construction.

Host: Graham Kribs

 

Date: Thursday, May 11th, 2017
Speaker: David Hestenes, Arizona State University

Title: Waves versus Particles: Hunting for Snarks in Quantum Mechanics

Abstract: gbcA long-standing debate over the interpretation of quantum mechanics has centered on the meaning of Schrödinger’s wave function y for an electron. Broadly speaking, there are two major opposing schools. On the one side, the Copenhagen school (led by Bohr, Heisenberg & Pauli) holds that y provides a complete description of a single electron state; hence the probability interpretation of yy* expresses an irreducible uncertainty in electron behavior that is intrinsic in nature. On the other side, the realist school (led by Einstein, de Broglie & Bohm) holds that y represents a statistical ensemble of possible electron states; hence it is an incomplete description of a single electron state. I contend that the debate has overlooked crucial facts about the electron revealed by structure in Dirac’s equation and its relation to Maxwell’s equation. First, analysis of electron zitterbewgung (noticed and named by Schrödinger) opens a window to particle substructure in quantum mechanics that explains the physical significance of the complex phase factor in y and relates it to electron spin. Second, the modulus of y can be given a physical interpretation as impedance of electron charge in the vacuum. This leads to a testable model for particle substructure in quantum mechanics with surprising theoretical and experimental implications. I give details and discuss prospects for encountering a Snark or a Boojum in the end. The perils of research on the foundations of quantum mechanics have been foreseen by Lewis Carroll in The Hunting of the Snark!

Biography:

David Hestenes is Emeritus Professor of Physics at Arizona State University and a Fellow of the American Physical Society (APS). He is principal architect of Geometric Algebra and Calculus as a unified mathematical language for physics and engineering. He has also developed a Modeling Theory of Cognition and Instruction with extensive applications to STEM education. In recognition of this work he was designated Foundations of Physics Honoree in 1993, awarded the 2002 Oersted Medal by the American Association of Physics Teachers, the 2003 Education Research Award by the National Council of Scientific Society Presidents, and the 2014 Excellence in Physics Education Award by the APS.

Host: Brian Smith

 

Date: Thursday, May 4th, 2017
Speaker: Rouven Essig, Stony Brook University

Title: The Next Frontier in Searching for Dark Matter

Abstract: Dark matter makes up 85% of the matter in our Universe, but we have yet to learn its identity. A broad array of search strategies are needed to probe for non-gravitational interactions between dark matter and ordinary matter. While most searches focus on Weakly Interacting Massive Particles

(WIMPs) with masses between 1 GeV and 1 TeV, it is imperative to also consider other dark matter candidates. In this talk, I will give a broad overview of the next frontier in searching for dark matter and related particles, such as dark photons, focusing on MeV-to-GeV masses. I will especially highlight novel dark matter direct-detection strategies that can probe dark matter in this mass range, several orders of magnitude below the WIMP scale. I will also mention new fixed-target and colliding-beam experiments. These ideas open up vast new regions of parameter space for experimental exploration in the next few years.

Host: Graham Kribs

 

Date: Thursday, April 27th, 2017
Speaker: Francisco Elohim Becerra, University of New Mexico

Title: Quantum Technologies for Optical Communication

Abstract: Quantum information science can enable communication technologies with capabilities surpassing those of current technologies. For example, by harnessing the quantum properties of light or single-photon detection, it is possible to devise measurements achieving sensitivities beyond the ultimate sensitivities of current coherent communication technologies. Furthermore, by using entangled pairs of photons it is possible to establish absolute secure communication via quantum key distribution, where security is guaranteed by the quantum properties of these photons. However, the ever-increasing need for higher transmission rates in communication will require future quantum technologies to be able to enhance information transfer for applications in classical or quantum communication, while extending communication links over long distances. Here, we describe our current work on quantum measurements with high sensitivity for states of light working as information carriers, and atom-photon interfaces based on atomic ensembles and single photons carrying information encoded in their spatial degrees of freedom. These interfaces can in principle allow for increasing information transfer in secure communication over long distances.

Host: Brian Smith

 

Date: Thursday, April 20th, 2017
Speaker:  Stephanie Simmons, Simon Fraser University

Title: The International Race For A Quantum Computer

Abstract: Silicon transistors, the essential building block of most modern electronic devices, cannot shrink much further without being rendered inoperable by quantum mechanics. This classical-quantum threshold in fact presents a tremendous opportunity: if we harness quantum mechanics, rather than attempt to avoid it, we could build a quantum computer. Quantum computers will open up a world of opportunities — they could accomplish certain computational tasks exponentially faster which would otherwise be forever impractical. During this lecture, Dr. Simmons will discuss various quantum computing approaches, how quantum technologies will change our lives in a very fundamental way, and provide a snapshot of the accelerating worldwide race to build a prototype.

Host: Brian Smith

 

Date: Thursday, April 13th, 2017
Speaker:  Martin Lavery, Royal Academy of Engineering Research Fellow, School of Engineering, University of Glasgow

Title: Communications with a Twist

Abstract: I will discuss my current findings in the development of point-to-point free-space links that employ spatial division multiplexing as a method to dramatically increase the available data rates and security in last-mile networks. The talk will give a brief overview of the state-of-the-art developments that are shaping the research field. The focus will be on my studies into the 1.6km propagation of optical beams that carry Orbital Angular Momentum, along with studies into a shorter link in an underwater environment. I will also discuss the use of plane-wave states as an alternative to Orbital Angular Momentum within a point-to-point free-space link.

Bio:
Martin completed his Ph.D at the University of Glasgow under supervision of Prof. Miles J. Padgett. After his Ph.D. he was awarded an EPRSC Doctoral Prize Fellowship to support his post doctoral research, and in 2013 he was Awarded the Scopus Young Research Award UK in the Physical Sciences. Martin is currently the holder of Royal Academy of Engineering Research Fellowship and is leading the Structured Photonics Research Group at the University of Glasgow.

Host: Benjamin McMorran

Date: Thursday, April 6th, 2017
Speaker: Victor Watson Brar, University of Wisconsin – Madison

Title: Probing Sub-Critical and Super-Critical Impurities in Graphene

Abstract: Graphene, an atomically thin sheet of carbon atoms, is a two dimensional semi-metal in which the electrons behave as massless Fermions. Because it is extremely thin and has a low carrier density, the local electronic structure of graphene can be strongly modified by impurities found either in the nearby environment, or introduced via intentional doping. This talk will discuss several impurity related phenomena that are observed in graphene and how they can modify the macroscopic properties that are observed in graphene devices. By using a scanning tunneling microscope to construct, atom-by-atom, different species of impurities, we will show that phenomena can be realized that are analogous to as-of-yet unobserved high energy physics effects. Namely, it will be shown that ‘super-critical’ impurities can be created in graphene, which demonstrate how electrons and positrons would behave around a nuclear core with Z > 173, where the binding energy of the electron exceeds 2m­ec2.

Host: Benjamín Alemán