Events at Physics

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Events on Tuesday, November 19th, 2013

Chaos & Complex Systems Seminar
A historical introduction to quantum computing
Time: 12:05 pm
Place: 4274 Chamberlin (refreshments will be served)
Speaker: Marty Lichtman, UW Department of Physics
Abstract: The quantum computer is on the horizon. If a system is small enough and isolated enough, it behaves according to the weird laws of quantum mechanics. One of the beautiful behaviors of a quantum system is that it can exist in a "superposition" of multiple states, at the same time. In the last two decades, physicists, including the 2012 Nobel laureates, have learned to control these systems. If we think of the state of these systems as a piece of information, we can store a superposition of data. Then by manipulating the system, a calculation is performed. The power of this quantum computation is that many calculations may effectively be performed at the same time. The potential speedup is immense. A functional quantum computer will certainly bring advances in cryptography, search, and physical simulation, and likely in all areas of science that have hard computational problems. This talk will present the development of the quantum computer in the historical context of classical computing. We will discuss the basics of how a quantum computer can speed up certain calculations, and also look at one experimental attempt to build a quantum computer using trapped neutral atoms here at UW-Madison.
Host: Clint Sprott
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Theory Seminar (High Energy/Cosmology)
Detecting dark Matter sub halos with Gaia
Time: 4:00 pm
Place: 5280 Chamberlin Hall
Speaker: Douglas Spolyar, Institut d’astrophysique de Paris
Abstract: Cold Dark Matter (CDM) theory, a pillar of modern cosmology and astrophysics, predicts the existence of a large number of starless dark matter halos surrounding the Milky Way (MW). However, clear observational evidence of these "dark" substructures remains elusive. Here, we present a detection method based on the small, but detectable, velocity changes that an orbiting substructure imposes on the stars in the MW disk. Using high-resolution numerical simulations we estimate that the new space telescope Gaia should detect the kinematic signatures of a few starless substructures provided the CDM paradigm holds. Such a measurement will provide unprecedented constraints on the primordial matter power spectrum at low-mass scales and offer a new handle onto the particle physics properties of dark matter.
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