| Institution | University of Toronto |
| Date of Colloquim | Jan 18 |
| Colloquium Title | The wonders of supersymmetry: from quantum mechanics, topology, and noise, to (maybe) the LHC |
| Supersymmetry is a quantum-mechanical symmetry relating bosons and fermions. It was discovered more than
35 years ago in quantum field theory and string theory, but the seeds of its ``miraculous" properties can
be seen already in quantum mechanics. This talk introduces supersymmetry via the supersymmetric
(an-)harmonic oscillator. We shall see that this seemingly trivial example is sufficiently rich to allow
us to illustrate how supersymmetry is used in a variety of fields: from mathematics and elementary
particle physics to critical phenomena and stochastic dynamics.
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| Host |
Keith Dienes |
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| Institution | U of A |
| Date of Colloquim | Jan 25 |
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| Institution | Harvard |
| Date of Colloquim | Feb 1 |
| Colloquium Title | Spin dynamics and the spin Hall effect in metallic nanostructures |
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Spintronics aims to replace charge with spin as the main computational element
in devices. Much effort is being devoted to understand how the electron spin is
transferred through interfaces and to identify fundamental processes that modify
the spin polarization or that can be used for spin manipulation. Lateral
structures are a unique tool to study these phenomena because of the ease to
fabricate them in multi-terminal configurations. This will be illustrated by
some of our recent experimental results in thin-film devices, where the output
voltage is exclusively determined by the spin degree of freedom and provides
valuable information on spin-flip scattering mechanisms, spin-polarized
tunneling, spin-orbit interaction and the spin Hall effect.
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| Institution | Princeton University |
| Date of Colloquim | Feb 8 |
| Colloquium Title | Topology of Large Scale Structure in the Universe |
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How the topology of large scale structure in the universe can be used to test the Gaussian random phase initial conditions predicted by inflation, and theories of galaxy formation, including non-linear effects and biasing.
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| Host |
Astronomy Department / Dr. Mark Dickinson |
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| Joint colloquium with the astronomy department - will take place @ Steward Observatory N210, 4:00pm, Feb 8
Refreshments will be available at 3:30pm in the Steward Observatory Lobby.
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| Institution | U of Wisconsin - Madison |
| Date of Colloquim | Feb 15 |
| Colloquium Title | Astronomy with Neutrinos |
| Abstract
Neutrinos are very promising messengers from the Universe since they are not
absorbed or deflected as much as
photons or protons. Astrophysical neutrinos have never been detected before
at energies above the TeV scale.
We look for them to provide information on the most powerful engines that
produce the Ultra-High Energy cosmic rays
that are observed in giant air showers.
We are building giant neutrino telescopes in the most unexplored regions of
our planet: the Antarctica and
the sea depths. I will describe where do these efforts stand and what we are
measuring now.
With unprecedented statistics, IceCube and ANTARES will also provide a lot
of information on the hadronic processes
that produce neutrinos in our atmosphere. The construction season of IceCube
will almost be concluded at the time of the colloquium and I will bring
fresh news from South Pole about an amazing enterprise: building a
cubic-kilometer array of photomultipliers between 1.5 and 2.5 km below the
ice surface.
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| Host |
Ina Sarcevic |
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| Institution | U of Illinois, Urbana-Champaign |
| Date of Colloquim | Feb 22 |
| Colloquium Title | Would Proposed Defenses Against Nuclear-Armed Long-Range Missiles Work?
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Since 1955, the United States has spent more than $200 billion developing and building a variety of
systems intended to defend the U.S. against nuclear-armed long-range ballistic missiles. Ultimately,
all of these systems were judged ineffective and most never became operational. The United States is
currently spending about $10 billion per year on systems to be based in the United States and Europe
that are intended to defend against missiles that might be acquired in the future by North Korea or
Iran. I will summarize the history of missile defense and missile defense technologies and discuss
whether the approaches now being pursued are likely to be more effective than those of the past.
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| Host |
D. Psaltis |
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| Institution | Duke |
| Date of Colloquim | Feb 29 |
| Colloquium Title | Effective Field Theories for Strongly Interacting Particles:
from Charmed Hadrons to Cold Atoms |
| In the last few years, electron-positron colliders have discovered
a multitude of new hadrons containing charm quarks. Because
of the confinement of quarks, calculating the properties of these
novel bound states poses a difficult problem in Quantum Chromodynanics
(QCD).
States of particular interest are excited even-parity charmed strange mesons
whose masses and widths are unexpectedly small, and the
X(3872), which is thought to be a molecular bound state of charmed mesons.
Effective field theories that combine the chiral and heavy quark
symmetries of QCD can be used to obtain qualitative insights into the
nature of these hadrons and make quantitative predictions for some of their
properties.
Effective theories for two-body systems with large scattering lengths,
developed in the late 90's for nuclear physics, are applied to the X(3872).
Symmetries of these theories that emerge when scattering lengths
diverge can also be used to make predictions for a very different strongly
interacting system: gases of cold trapped fermionic atoms whose scattering
length is tuned to infinity via a Feshbach resonance.
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| Host |
S. Fleming |
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| Institution | Fermilab |
| Date of colloquium | March 7 |
| Colloquium Title | A New Muon to Electron Conversion Experiment |
| Charged lepton flavor violation is a nearly universal
feature of Beyond-Standard-Model physics. In particular,
the conversion of a muon to electron after capture on
a nucleus would be a clean and unambiguous signature
for new physics. This talk will cover the history
and prospects in this area, with focus on a new
experiment being proposed for Fermilab after the
end of the current collider program.
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| Host |
Erich Varnes |
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| Institution | University of Texas, Austin |
| Date of colloquium | March 28 |
| Colloquium Title | Room-Temperature Counterflow Superfluidity in Graphene Bilayers |
| It has been realized since the 1960's that semimetals would have
a superfluid ground state with condensed excitons if their conduction and
valence band Fermi surfaces were very similar. Unfortunately it seems that
this nesting requirement is never satisfied sufficiently well in natural
materials. I will discuss our proposal that exciton condensation states
will appear and survive to elevated temperatures in artificial materials
based on graphene, a newly realized atomically two-dimensional form of many
which consists of carbon atoms on a honeycomb lattice. Room temperature
exciton condensates could lead to a radically new type of electronic
technology.
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| Host |
Philippe Jacquod |
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| Institution | Georgia Tech |
| Date of colloquium | April 4 |
| Colloquium Title | Near-wall velocimetry in microscale flows |
| Although fluid flows at the micro- and nanometer scale have recently become of interest, there are few experimental techniques at present with a spatial resolution fine enough measure velocity fields in these flows. This talk introduces a technique using evanescent-wave illumination generated by total internal reflection of light at the fluid-wall interface. This technique, nano-particle image velocimetry (nPIV), measures the velocity components tangential to and within about 400 nanometers of the wall using fluorescent colloidal (100-200 nm diameter) polystyrene tracers under the assumption that these particle tracers follow the flow with good fidelity. The technique has been used to measure velocity profiles in steady and fully-developed electroosmotic flow. Results for very dilute monovalent aqueous solutions suggest that nPIV has a near-wall spatial resolution sufficient to resolve the velocity defect predicted by theory inside the diffuse electric double layer.
More recently, nPIV has been extended to multilayer nPIV (mnPIV), where the exponential decay in the evanescent-wave intensity with wall-normal distance z is used to obtain velocities at different values of z. The feasibility of this technique has been tested for images of particles convected by steady Poiseuille flow through 40 micrometer microchannels. The mnPIV data show that the colloidal tracers are nonuniformly distributed in z within 400 nm of the wall, with almost no tracers within about 100 nm of the wall, most likely due to electrostatic effects. Results obtained for water and monovalent aqueous electrolyte solutions show that the tracer distribution is strongly affected by the pH and electrolyte composition of the working fluid. With appropriate correction, estimates of velocity gradients (and hence wall shear stress) obtained with mnPIV are in all cases within 8% of the values predicted by the classic solution for two-dimensional Poiseuille flow. The effects of this markedly nonuniform tracer distribution and asymmetric and hindered Brownian tracer diffusion on near-wall velocimetry data and its implications for near-wall velocity measurements are briefly discussed.
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| Host |
John Kessler |
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| Institution | Penn State University
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| Date of colloquium | April 11 |
| Colloquium Title | A Neutrino Perspective on the Universe
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| The neutrino discoveries of the last decade have brought the first
experimental evidence of particle physics beyond the Standard
Model. We are now moving into the era of using neutrinos as a tool for
learning about particle astrophysics and new physics phenomena. I will
briefly review the history of solar neutrinos, which puts into
perspective both challenges and opportunities of using neutrinos to
learn about physics and astrophysics. I will then discuss prospects for
future high energy neutrino detection and how this data can be used to
learn about new phenomena.
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| Host |
Ina Sarcevic |
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| Institution | Director, Office of Research, Development & Simulation,
National Nuclear Security
Organization,
Washington, DC |
| Date of colloquium | April 18 |
| Colloquium Title | The New Frontier of Computational Science:
Applications to High Leverage Decisions
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| Today our supercomputers have already surpassed the half-petaflop mark,
and are nearing sustained performances at the petascale. Is there
something new to be had at a petaflop, or should we expect more of the
same, only faster? While there are many technical challenges at this
scale, I believe it symbolizes the scale at which our approach to
computational science - today's archetype - requires revision. We are
reaching the point where raw computational power is no longer the
limiting factor - rather what constrains us is our vision and our
ability to ensure the veracity of our predictions. Computing at the
petascale will open doors to discovery, and we must not be limited by
the current way we approach computing. At the same time, expectations
for great achievement will likely outpace our ability to effectively use
these systems for innovation. This is becoming critical as these
results have the potential to exert greater influence on
high-consequence decisions
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| Host |
Philippe Jacquod |
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| Institution | Duke University |
| Date of colloquium | April 25 |
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| Host |
Charles Stafford |
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| Date of colloquium | May 2 |
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| Host |
Dimtrios Psaltis |
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| Institution | Cornell |
| Date of colloquium | May 9 |
| Colloquium Title | Quantum transport and its classical limit |
| The interference of multiply scattered quantum mechanical matter waves causes small but noticeable
corrections to the electrical conduction of a metal at low temperatures. What is the fate of quantum
interference corrections in the limit that the wavelength of the electrons becomes small in comparison to
all other relevant length scales? This limit is a "classical limit" similar to the transition from wave
optics to ray optics that occurs when the typical size of optical elements becomes much larger than the
wavelength of light. Surprisingly, the answer is not at all trivial: Whereas the interference correction
to the ensemble-averaged conductance (weak localization) disappears in this classical limit, the quantum
interference contribution to the sample-specific conductance fluctuations survives.
The "classical limit" is relevant for conductors in which the electron motion is ballistic and the only
source of scattering is specular reflection off sample boundaries or artificial macroscopic scattering
sites. In this talk, I'll outline the basic structure of a theory of quantum transport in ballistic
conductors, as well as possible experimental signatures that distinguish ballistic conductors and their
disordered counterparts.
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| Host |
Philippe Jacquod |
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