## Events at Physics |

### Events on 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