Colloquia & Seminars
  • JQI Seminar
    Speaker Name: Hartmut Haeffner

    Speaker Institution: UC Berkley

    Title: Quantum information, quantum correlations and a Michelson-Morley test with electrons

    Abstract: Quantum information processing promises to speed up certain computational tasks. The expectations are high, but many technological hurdles have to be overcome before we can build a quantum computer. Nevertheless, already today quantum information allows for novel insights into physics. In this talk, I will summarize our progress towards building an ion trap quantum computer. In addition, I will discuss experiments studying the dynamics of quantum correlations in ion strings as well as a surprising application of quantum information to fundamental physics. Using the precise experimental control over individual ions, we verify Lorentz invariance at a level of 10-18, improving the limits set by traditional Michelson-Morley experiments by a factor of five
    When: Mon, February 2, 2015 - 11:00am
    Where: 2400 Computer and Space Sciences
  • Biophysics Seminar
    Speaker Name: Min Zhao

    Speaker Institution : UC-Davis

    Title : Electrical Control of Cell Migration in Wound Healing.

    Abstract: Wounds naturally generate weak direct current electric fields. We study how this type of electrical signals may regulate cell behavior during wound healing. This type of physiological electric fields/currents provides a powerful cue to induce polarized activation of intracellular signaling pathways and directional migration of cells. The guidance effect may override other well accepted directional signals such as contact inhibition release, chemotaxis and mechanical forces following injury. We aim to understand how the electrical signals are produced, what mechanisms the very weak electric fields guide cell migration, and to develop technology to exploit this unique signal to facilitate wound healing.
    When: Mon, February 2, 2015 - 4:00pm
    Where: 0112 Chemistry Bldg.
  • EPT Seminar
    Title: New Insights into Cosmic Abundances of Matter and Related Phenomenology

    Speaker: Yanou Cui, Perimeter Institute

    Abstract: I will review prominent puzzles about the cosmic relic abundances of atomic matter and dark matter, and discuss new theoretical ideas/models to address these puzzles. The connection of these theories with new particle physics frontiers such as the Higgs mechanism and supersymmetry will be discussed. I will also demonstrate the rich phenomenological predictions from these theories that can be tested in a variety of experiments such as with neutrino detectors and the Large Hadron Collider (LHC).
    When: Mon, February 2, 2015 - 4:00pm
    Where: PSC 3150
  • Educational Psychology Colloquium: Joe Redish
    Dr. Joe Redish will be speaking to the Department of Human Development & Quantitative Methodology at its Educational Psychology Colloquium.

    The talk will be held Tuesday, February 3, from 12:30 to 1:30 PM, in Benjamin Building room 3233. Lunch will be provided starting at 12:15 PM. Dr. Redish will be giving a talk entitled:

    "Epistemological framing: The role of selective attention in building rich knowledge structures."

    Thanks and we hope to see anyone who is interested next week!
    Emily Rosenzweig < This e-mail address is being protected from spambots. You need JavaScript enabled to view it >
    When: Tue, February 3, 2015 - 12:30pm
    Where: 3233 Benjamin Building
  • Informal Statistical Physics Seminar
    Speaker Name: Mohammad Hafezi

    Speaker Institution: UMD

    Title: Engineering thermalization and chemical potential for photons

    Abstract: Photons are not conserved in interactions with other matter. Consequently, when understanding the equation of state and thermodynamics of photons, while we have a concept of temperature for energy conservation, there is no equivalent chemical potential for particle number conservation. However, the notion of a chemical potential is crucial in understanding a wide variety of single- and many-body effects, from transport in conductors and semi-conductors to phase transitions in electronic and atomic systems. Here we show how a direct modification of the system-bath coupling via parametric oscillation creates an effective chemical potential for photons even in the thermodynamic limit. Specific implementations, using circuit-QED or optomechanics, are feasible using current technologies, and we show a detailed example demonstrating the emergence of Mott Insulator-superfluid transition in a lattice of nonlinear oscillators. Our approach paves the way for quantum simulation, quantum sources and even electron-like circuits with light.

    When: Tue, February 3, 2015 - 1:15pm
    Where: Room 1116 IPST Building (Bldg. 85)
  • Physics Colloquium - Elizabeth Hayes NASA
    Speaker Name: Elizabeth Hayes

    Speaker Institution: NASA

    Title: New Views of the Galaxy in Gamma Rays from the Fermi Gamma-ray Space Telescope

    Abstract: Over the past 6 years, NASA’s Fermi Gamma-ray Space Telescope has revolutionized our view of the Milky Way. Fermi’s Large Area Telescope
    (LAT) continues to deepen and sharpen our picture of the high energy sky from 100 MeV to > 300 GeV. Of the more than 3000 sources in the third LAT catalog, nearly 9% are associated with sources in our own Galaxy while many others remain to be associated. New classes of gamma-ray emitters have been discovered and previously known classes of emitters have been studied in fantastic detail. LAT data have revealed for the first time a large-scale feature of the Milky Way, dubbed the Fermi Bubbles. For much of the past year, Fermi employed a modified sky survey to gain additional exposure toward the Galactic Center and to shed light on the unexplained excess of gamma rays observed by LAT in that region and the possible interpretation as a dark matter signal. I’ll give an overview of key results from the Fermi mission and its continued role in understanding energetic phenomena in our Galaxy.

    When: Tue, February 3, 2015 - 4:00pm
    Where: PSC Lobby
  • The Man Who Saved the World screening
    The Center for International and Security Studies at Maryland (CISSM) will present the film, “The Man Who Saved the World,” which documents the life of Soviet military officer Stanislav Petrov, who by all accounts single-handedly averted an accidental nuclear exchange between the USSR and US in 1983. The screening is part of a nationwide screening day for the film. The event is open to the public and free, and a brief discussion led by School of Public Policy faculty will follow.

    When: Tue, February 3, 2015 - 6:30pm
    Where: 1212 Van Munching Hall (Tyser Auditorium)
  • Nuclear Physics Seminar
    Title: The EOS of neutron matter, and the effect of Lambda hyperons to neutron star structure

    Speaker: Stefano Gandolfi, Los Alamos National Lab

    Abstract: Recent advances in experiments of the symmetry energy of nuclear
    matter and in neutron star observations yield important new insights
    on the equation of state of neutron matter at nuclear densities.
    In this regime the EOS of neutron matter plays a critical role in
    determining the mass-radius relationship for neutron stars. We show how
    microscopic calculations of neutron matter, based on realistic two- and
    three-nucleon forces, make clear predictions for the relation between the
    isospin-asymmetry energy of nuclear matter and its density dependence,
    and the maximum mass and radius for a neutron star.

    On the other side, several microscopic calculations suggested that the
    inclusion of hyperons softens the EOS such that the corresponding maximum
    mass of neutron stars is much lower that astrophysical observations.
    We will show that very small changes in the nucleon-nucleon-Lambda interactions
    have a dramatic role to the EOS, while hypernuclei are quite insensitive to
    the same adjustments.
    When: Wed, February 4, 2015 - 1:00pm
    Where: PSC 3150
  • Lab for Physical Sciences Seminar
    Speaker Name: Dr. Jay Sau

    Speaker Institution: UMCP

    Title: Long-range anti-ferromagnetic interactions and near zero-energy states in magnetic impurities in superconductors

    Abstract: Magnetic impurities in superconductors are known to host sub-gap Yu-Shiba-Rusinov bound states that have been observed in scanning tunneling microscopy (STM) experiments. In the first part of this talk, I will discuss how the presence of these YSR states modifies the interaction between the impurity spins [1]. The YSR states bound to the spins modify the interaction energy between the spins from the oscillating RRKY type to dominantly anti-ferromagnetic at distances larger than the fermi wave-length but small compared to the coherence length. This provides a potentially interesting scenario where many quantum spins can interact with each other through the superconductor to lead to interesting ground states. In the second part of this talk we will discuss recent STM experiments involving multiple magnetic impurities where near zero-energy states have been observed and interpreted to be Majorana modes. We will discuss a recent theoretical mechanism of how low energy YSR states can appear in complex magnetic impurities [2].

    [1] N. Y. Yao, L. I. Glazman, E. A. Demler, M. D. Lukin, J. D. Sau, Phys. Rev. Lett. 113, 087202 (2014).

    [2] J. D Sau, P. Brydon, arXiv:1501.03149.

    Notes: For guests attending the LPS seminar, please use the phone on the left hand side of the front door to call the receptionist for entry. LPS is located at 8050 Greenmead Drive in College Park. There is parking at LPS and overflow parking at the adjacent LTS building but not at the 4H building. LPS is on the UMCP shuttle route; take #105 for the Courtyard Apts.

    When: Wed, February 4, 2015 - 3:30pm
    Where: Lab for Physical Sciences downstairs conference room
  • Plasma Physics Seminar
    Speaker Name: Prof. Cary Forest

    Speaker Institution: University of Wisconsin, Madison

    Title: Chasing Fast Dynamos and Other Pursuits
    When: Wed, February 4, 2015 - 4:00pm
    Where: ERF 1207
  • Refreshments for CNAM Colloquium

    When: Thu, February 5, 2015 - 1:30pm
    Where: The "new" Toll Room, Phys. Rm 1305F
  • CNAM Cond. Matter Colloquium
    Speaker Name: Prof. Ian Appelbaum

    Speaker Institution: UMD

    Title: Symmetry, Dimension, and Spin: Understanding transport in 2D ‘phosphorene’

    Abstract: Despite its low atomic number and inversion symmetry, recent electronic measurements demonstrate that (group-IV) graphene has a greatly disappointing spin lifetime, corroborated by theory showing strong spin-flip scattering by flexural (out-of-plane) phonons. There exists a class of graphene-like 2-dimensional semiconductors formed from elemental group-IV OR group V atoms, some of which may be immune to this deleterious coupling. Only one is known to mechanically exfoliate like graphene: phosphorene (monolayer black phosphorus). We analyzed the symmetry of its electronic bandstructure including spin-orbit interaction close to the insulating gap edge with special interest in the spin-transport properties. Importantly, we discovered that the natural buckling of the honeycomb crystal lattice results in anisotropic spin flip processes that are entirely decoupled from flexural phonons for a particular in-plane spin orientation. This discovery allows us to predict a spin lifetime comparable to bulk Si, vastly greater than graphene.
    This work is based on P. Li and I. Appelbaum, Phys. Rev. 90, 115439 (2014).
    When: Thu, February 5, 2015 - 2:00pm
    Where: Phys Rm 1201
  • Lott's paper on torsion constraints, part 1
    We will begin studying Lott's paper "The Geometry of Supergravity Torsion Constraints", arXiv:math/0108125. For more details see Comm. Math. Phys. 133 (1990), 563–615, though the arxiv paper is shorter and easier to read.
    When: Thu, February 5, 2015 - 3:30pm
    Where: PHY 1117
  • EPT Seminar
    Title: tk

    Speaker: Luca Vecchi, UMD

    Abstract: tk
    When: Thu, February 5, 2015 - 4:00pm
    Where: PSC 3150
  • Materials Science and Engineering seminar
    Speaker Name: Wangchun Chen

    Speaker Institution : NIST Center for Neutron Research

    Title : Polarized Neutron Developments at the NIST Center for Neutron Research

    Abstract : Polarized neutron scattering is a powerful tool to probe magnetic structures over a variety of length scale, magnetization density and magnetic excitations in a wide range of magnetic materials in physics, chemistry, material science and earth science. However polarized neutron scattering is one of the most challenging neutron instrumentation techniques due to significant intensity reduction from polarized beam production and analysis, necessity of precise spin manipulation, and complicated data reduction and analysis. Using a novel neutron polarizing device, nuclear-spin-polarized 3He neutron spin filter (NSF), polarized neutron measurement capabilities have been significantly advanced during the last several years at the NIST Center for Neutron Research (NCNR). I will outline developments of polarized neutron instrumentation using polarized 3He NSFs, including thermal triple axis spectrometry, small-angle neutron scattering, wide-angle polarization analysis, and diffuse reflectometry. These advanced polarized neutron measurement capabilities at the NCNR are opening new scientific opportunities to studies of magnetic nanoparticles assemblies, multiferroics, superconductors, exchange-biased systems, and giant magnetostrictive materials. Examples of such scientific applications will be presented. Finally I will discuss a recent observation of world record high (up to 88%) 3He polarizations achieved by the spin-exchange optical pumping method.

    When: Fri, February 6, 2015 - 1:00pm
    Where: Room 2108, Chemical and Nuclear Engineering Bldg.
  • EPT Seminar
    Title tk

    Speaker: David Yaylali, University of Arizona

    Abstract: tk
    When: Mon, February 9, 2015 - 4:00pm
    Where: PSC 3150
  • Informal Statistical Physics Seminar
    Speaker Name: Professor Tongcang Li

    Speaker Institution : Purdue University

    Title : Brownian Motion at Short Time Scales.

    Abstract: Brownian motion has played important roles in many different fields of science since its origin was first explained by Albert Einstein in 1905. Einstein's theory of Brownian motion, however, is only applicable at long time scales. At short time scales, Brownian motion of a suspended particle is not completely random, due to the inertia of the particle and the surrounding fluid. Moreover, the thermal force exerted on a particle suspended in a liquid is not a white noise, but is colored. Recently, we developed an ultrasensitive optical tweezer, and measured the instantaneous velocity of a Brownian particle in both gas and liquid. This ultrasensitive optical tweezer provides a powerful tool for studying statistical mechanics of small systems. References: T. Li, et al. Science, 328, 1673 (2010). S. Kheifets, et al. Science, 343, 1493 (2014).

    When: Tue, February 10, 2015 - 1:15pm
    Where: Room 1116, IPST Building, Bldg 85
  • Physics Colloquium - John Carlstrom
    Speaker Name: John Carlstrom

    Speaker Institution: University of Chicago

    Title: Physics and Cosmology with the Cosmic Microwave Background

    Abstract: The study of the cosmic microwave background (CMB) has driven spectacular advances in our understanding of the origin, make up and evolution of our universe. We now have a standard cosmological model, LCDM, that fits all the cosmological data with only six parameters, although there are some tensions that may hint at that cracks in the model. Far from being the last word in cosmology, the model points to exciting times ahead using the CMB to explore new physics, i.e., inflation, dark matter, dark energy, neutrino masses and possible additional relativistic species, or dark radiation. This talk will review the current status and near term plans for CMB measurements, with emphasis on the South Pole Telescope, and discuss the plans for the next generation experimental program, CMB-S4.
    When: Tue, February 10, 2015 - 4:00pm
    Where: PSC Lobby
  • Nuclear Physics Seminar
    Title: tk

    Speaker: Thomas Schaefer, North Carolina State

    Abstract: tk
    When: Wed, February 11, 2015 - 1:00pm
    Where: PSC 3150
  • Refreshments for CNAM Colloquium

    When: Thu, February 12, 2015 - 1:30pm
    Where: The "new" Toll Room, Phys. Rm 1305F

Department of Physics

University of Maryland
College Park, MD 20742-4111
Phone: 301.405.3401
Fax: 301.314.9525