# This Week at Physics

## Events at Physics |
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### Events During the Week of November 25th through December 2nd, 2018

### Monday, November 26th, 2018

**Plasma Physics (Physics/ECE/NE 922) Seminar****Turbulent Dynamo in a Collisionless Magnetized Plasma****Time:**12:05 pm**Place:**2241 chamberlin hall**Speaker:**Denis St-Onge, Princeton Univ.**Abstract:**The Universe is magnetized. While magnetic-field strengths of just ~10-18 G are required to achieve this both in our Galaxy and in clusters of galaxies, observations of Faraday rotation, Zeeman splitting, and synchrotron emission all make the case of ubiquitous microgauss fields. That these systems are not content with hosting weaker fields is surprising, at least until one realizes that the energy density of a microgauss field is comparable to that of the observed turbulent motions. It is then natural to attribute the amplification and sustenance of (at least the random component of) the interstellar and intracluster magnetic fields to the fluctuation (or “turbulent”) dynamo. In this talk, we will explore the various ways in which plasma microphysics makes magnetic-field amplification in weakly collisional plasmas by macroscale turbulent motions possible, with application to the intracluster medium of galaxy clusters.### Tuesday, November 27th, 2018

**Chaos & Complex Systems Seminar****Solar activity and its influence on us****Time:**12:05 pm**Place:**4274 Chamberlin (Refreshments will be served)**Speaker:**Alex Lazarian, UW Department of Astronomy**Abstract:**The Sun is a magnetically active star. Solar activity results in inducing the solar wind as well as generating the energetic particles. The solar wind affects the size of the heliosphere around the solar system and this induces modulation of the galactic cosmic rays arriving to the Earth. Energetic particles from the Sun interact with the Earth's magnetic field and cause electromagnetic storms. I shall discuss how the Sun affects the Earth ecosystem.**Host:**Clint Sprott**Council Meeting****council meetings****Time:**3:30 pm**Place:**2314 Chamberlin Hall**NPAC (Nuclear/Particle/Astro/Cosmo) Forum****New Physics and New Proposal to Find Them in Proton Fixed-Target Facilities at Fermilab****Time:**3:30 pm**Place:**4274 Chamberlin Hall**Speaker:**Yu-dai Tsai, FNAL**Abstract:**We propose a dedicated search for minicharged particles (MCP) and light dark matter at Fermilab utilizing proton-fixed target facilities. First, we present the constraints and sensitivity reaches considering the MCP scattering with the electrons in the neutrino detectors, including SBND, MiniBooBE, MicroBooNE, DUNE, and SHiP [1]. Secondly, we present a new proposal, FerMINI, to place a new detector to further improve the sensitivity. The potential sites include the MINOS hall downstream of NuMI beamline and the proposed DUNE near detector hall along the LBNF beamline. The setup would drastically improve the sensitivity of MCPs in the MeV to GeV mass regime and will be discussed in detail in this talk. I will also talk about the searches of other weakly interacting particles, including light scalars, dark photons, and dipole portal heavy neutral leptons (an explanation of MiniBooNE anomaly) [2, 3] if time allows. [1] arXiv:1806.03310 [2] arXiv:1803.03262 [3] arXiv:1706.00424**Host:**Carlos Arguelles### Wednesday, November 28th, 2018

**No events scheduled**### Thursday, November 29th, 2018

**R. G. Herb Condensed Matter Seminar****Modern Quantum Computing on Near Term Hardware. … over the cloud****Time:**10:00 am**Place:**5310 Chamberlin Hall**Speaker:**Dr. Raphael Pooser, Oak Ridge National Lab**Abstract:**In this talk I will outline recent advances in the field of computing enabled by quantum mechanics. Quantum computing is poised to enter into an era where computational power surpasses what classical machines can do. In this near-term era, when devices are not yet fault tolerant, but still out of reach of classical computers, the challenge is to harness them for useful computation despite the presence of significant noise in these systems. In particular, error mitigation is required to obtain useful results from these systems. We will outline several error mitigation techniques and show how they can be used in combination. One of the immediate applications on near term hardware include optimization of sampling from unknown probability distributions, which have applications in a broad array of quantum simulations, from chemistry to nuclear physics to field theory problems. After a brief review of the field, we will discuss several current architectures and applications of quantum computing.**Host:**Saffman**NPAC (Nuclear/Particle/Astro/Cosmo) Forum****Supernova Cosmology Results from the Dark Energy Survey****Time:**12:00 pm**Place:**4274 Chamberlin Hall**Speaker:**Richard Kessler, University of Chicago**Abstract:**Roughly 9 months after the end of the 5-year transient search in the Dark Energy Survey (DES), DES submitted a series of papers describing its first cosmology results based on measuring cosmic distances for a small fraction of the Type Ia Supernova sample. I will give an overview of DES, our first results, and the analysis, highlighting where we have made improvements necessary to reduce uncertainties. I will also briefly describe future prospects for SN Ia cosmology with DES (full sample) and the WFIRST space mission.**Host:**Keith Bechtol**Astronomy Colloquium****"Surveying the Galactic Bulge for Transients and Compact Binaries"****Time:**3:30 pm**Place:**4421 Sterling Hall, Coffee and Cookies 3:30 PM, Talk begins at 3:45 PM**Speaker:**Tom Maccarone, Texas Tech University**Abstract:**Understanding the evolution of binary stars is vital for almost all of the key problems in astrophysics today. For example, gravitational wave sources and Type Ia supernovae are fundamentally binary processes. From a theoretical point of view, binary stellar evolution is extremely complicated, with many poorly understood processes contributing. To build up an understanding of binary evolution, it is thus necessary to build a set of observational constraints. Here, I will present the results from several projects aimed at understanding the binary and transient populations of the Milky Way's Galactic Bulge. Some key highlights will include new understanding of cataclysmic variables, accreting black holes and neutron stars, and the discovery of a low mass protostar that appears to have formed in isolation.

**Host:**Sebastian Heinz, Chair Astronomy Department### Friday, November 30th, 2018

**Theory Seminar (High Energy/Cosmology)****Topological Data Analysis for Cosmology and String Theory****Time:**2:00 pm**Place:**5280 Chamberlin Hall**Speaker:**Alex Cole, University of Wisconsin-Madison**Abstract:**Persistent homology, the main technique underlying the field of Topological Data Analysis, computes the multiscale topology of a data set by using a sequence of discrete complexes. Roughly speaking, persistent homology allows us to compute the “shape” of data. In this talk I will introduce persistent homology and describe applications to data sets in cosmology and string theory. I will demonstrate how persistence diagrams provide an improved real-space observable for the Cosmic Microwave Background. In particular, persistence diagrams are more sensitive to local non-Gaussianity on a set of simulated temperature maps than Betti numbers, which are in turn more sensitive than the genus. I will also use persistent homology to characterize distributions of Type IIB flux vacua and as a framework for understanding the correlation of different low-energy features in moduli space.**Physics Department Colloquium****Special Event: Julian E. Mack Lecture****Quantum Information and Computation****Time:**3:30 pm**Place:**2241 Chamberlin Hall**Speaker:**David Wineland, U Oregon**Abstract:**Quantum systems such as atoms can be used to store information. For example, we can store a binary bit of information in two energy levels of an atom, labeling the state with lower energy a “0" and the state with higher energy a “1.” However, quantum systems can also exist in superposition states, thereby storing both states of the bit simultaneously, a situation that makes no sense in our ordinary-day experience. This property of quantum bits or “qubits” potentially leads to an exponential increase in memory and processing capacity. It would enable a quantum computer to efficiently solve certain problems such as factorizing large numbers, a capability that could compromise the security of current encryption systems. It could also be used to simulate the action of other important quantum systems in cases where such a simulation would be intractable on a conventional computer. A quantum computer could also realize an analog of "Schrödinger's Cat," a bizarre situation where a cat could be simultaneously dead and alive. Experiments whose goal is to realize a quantum computer based on laser manipulations of atomic ions will be described, but this is only one of several possible platforms for such a machine.**Host:**Alex Levchenko