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Fall 2020

September 4, 2020 (Friday) 4:00-5:00p.m. 
Shiwei Zhang, William & Mary and Flatiron Institute
H. Krakauer
Towards the solution of the many-electron problem: properties of the hydrogen chain
Abstract: Materials in which electrons strongly interact with one another exhibit a fascinating variety of structural, electronic and magnetic properties. Capturing the many underlying effects responsible for these properties is essential for understanding and predicting material behavior but requires a reliable treatment of the many-electron Schrodinger equation, which is a grand challenge in modern physics and chemistry. I will discuss an in-depth study of the quantum-mechanical ground state of what is perhaps the simplest realistic model for a bulk material: an infinite chain of equally spaced hydrogen atoms.The combined use of cutting-edge computational methods reveals a rich phase landscape that sheds light on the variety of material properties. This work establishes the hydrogen chain as a key benchmark for further methodological developments and an important model system for correlated electron systems. The results will motivate experimental realizations and stimulate further efforts to characterize phase diagrams of low-dimensional materials.

September 18, 2020 (Friday) 4:00-5:00p.m. 
Speaker: Srimoyee Sen (Iowa State)
Host: C. Monahan
Title: Particle vortex statistics and the phases of dense matter
Abstract: Neutron stars are extremely dense objects where atomic nuclei dissolve to produce extended soup of nucleons/baryons. Recent observation of neutron star mergers through gravitational waves has given rise to vigorous research activity in this area. In order to make progress in understanding neutron stars, it is of utmost importance to understand the properties of such dense matter as well as accurately model its equation of state. In this talk I discuss the various patterns of organizations expected to arise in dense baryonic matter and how modern developments in topological phase transitions in condensed matter systems combined with perturbative techniques in quantum chromodynamics, the theory of strong interactions, can inform our knowledge in this regard.

September 25, 2020 (Friday) 4:00-5:00p.m. 
Greg De Temmerman (ITER)
S. Mordijck
ITER: the technical and scientific challenges of controlling nuclear fusion
Nuclear fusion is the process that powers the Sun and stars in the universe. Harnessing this process on earth as a low-carbon source of energy remains one of the greatest scientific challenges of the 21st century. Research in controlled fusion started after WWII and steady progress has been achieved over the years although it proved considerably more difficult than initially anticipated. This is due to a combination of the complex physics of plasmas heated to over 100 million degrees C, and the technological challenges of “putting the sun in a box”.

ITER, currently being built in Southern France, aims at producing 500 MW of output thermal power for durations of ~400s, thereby demonstrating the scientific and technological feasibility of fusion power for peaceful purposes. It is based on the tokamak principle whereby the plasma is confined in the shape of a donut by a combination of strong magnetic fields, created by some of the largest superconducting magnets. ITER is one, if not the, most complex machines ever built, with dimensions of 30x30 m and a weight of 23,000 t and about a million of components to be assembled with very tight tolerances.

Started in 2006, ITER is a major international collaboration involving Europe, China, India, Japan, the Russian Federation, South Korea and the USA. After a difficult start, the project has reached in 2020 a critical milestone with the installation of the most massive component- the cryostat base- marking the start of the tokamak assembly, which will last about 4 years.

This talk will give a general introduction on nuclear fusion and on the physics which defined the size and design of ITER. It will cover the unique aspects of the project in terms of organization and engineering, and discuss the scientific and technical goals of the project. Finally, it will highlight the recent progress in the machine assembly and show how this long-dreamt machine is coming together.

Bio: Greg De Temmerman is a scientist working on nuclear fusion since the start of his PhD in 2003. He specialises in the study of the intense interactions between fusion plasmas and surrounding materials. He has worked in several laboratories including UCSD, CCFE (UK) and DIFFER (NL) before joining the ITER Organization in 2014 as a coordinating scientist for plasma edge and plasma-wall interactions, having the opportunity to contribute to this gigantic endeavour that the ITER project is. During his spare time he is also a passionate ultra-trail runner.

October 9, 2020 (Friday) 4:00-5:00p.m. 
Elizabeth Goldschmidt  (U. Illinois Urbana-Champaign)
I. Novikova
Quantum information with photons
Quantum information has the potential to be a transformative technology in the coming decades enabling secure information sharing, fundamental metrological advantages, and massive computational speedup for some classically intractable problems. Light plays an important role in many quantum information systems, particularly for transmitting quantum bits, or qubits. I will give a broad overview of the role that optical photons can play in quantum computing and quantum networking. This includes a discussion of generating light that is suitable for quantum information applications, inducing effective interactions between photons to enable entangling operations, and engineering light-matter interfaces for reversible mapping of quantum information. I will highlight recent experimental results to illustrate all of these research goals.

Elizabeth Goldschmidt is an Assistant Professor of Physics at the University of Illinois at Urbana-Champaign where she runs an experimental research group focusing on quantum optics and quantum information. She received her bachelors in physics from Harvard University in 2006 and her doctorate in physics from the University of Maryland in 2014, where her graduate research focused on single photon technologies and optical quantum memory. She was a National Research Council postdoctoral fellow at the National Institute of Standards and Technology from 2014-2016 where she studied ultracold and Rydberg excited atoms in optical lattices for quantum simulation. She was a staff scientist at the US Army Research Laboratory studying quantum optics in solid-state systems before joining the UIUC faculty in the fall of 2019.