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Colloquium

Unless otherwise noted, the physics colloquia are held in Room 307 of the Science and Engineering Research Facility. Refreshments are served at 3:00 p.m. with the talk following at 3:30. Please note: beginning in Fall 2017 colloquia were not webcast or recorded. The department is evaluating new cost models and options.

The Spring 2017 colloquia are available here, with the archives from previous semesters available Webcast archives.

Spring 2018 Schedule
Date
Speaker
Title
Host

January 22

Gerardo Ortiz
Indiana University

The Majorana Mysteries

Cristian Batista

January 29

Alison Sweeney
University of Pennsylvania

Max Lavrentovich

February 5

Gang Cao
University of Colorado

The Power of Strong Spin-Orbit Interactions:Challenges and Opportunities in Iridates

Haidong Zhou

February 12

Robert Pattie

Yuri Kamyshkov

February 19

February 26

Brian Nord
Fermilab

Sowjanya Gollapinni

March 5

Susan Blessing
Florida State University

Nadia Fomin

March 12

Spring Break

March 19

March 26

Michelle Dolinski
Drexel University

Nadia Fomin

April 2

Nian Sun
Northeastern University

Jian Liu

April 9

Leah Broussard
Oak Ridge National Laboratory

Yuri Kamyshkov

April 16

H.L. Dodds
IBM Professor, Emeritus, UT Nuclear Engineering

Energy Choices and Consequences

Bill Bugg

April 23

Physics Honors Day


Abstracts
January 22
Gerardo Ortiz, Indiana University

The Majorana Mysteries

On March 25th 1938 at the age of 32 years Ettore Majorana vanished, under mysterious circumstances, without leaving a trace. Only recently his name re-emerged as the Majorana fermion, a quasi-particle excitation that represents it own anti-quasi-particle, has been claimed to be detected by several experimental groups. Majorana fermions dance in a superfluid background. They have the potential to make quantum computers robust because of the special topological property of non-Abelian braiding, generated whenever Majorana fermions are transported around each other. But, what property distinguishes topologically trivial from non-trivial superfluids, supposedly hosting Majorana fermions? What is the meaning and fate of such excitations in closed, number conserving, interacting fermionic superfluids? I will attempt to answer these questions from both basic physics principles and concrete model perspectives. In particular, I will discuss a novel and realistic route to topological superfluidity realizable in repulsive ultracold alkaline-earth atomic systems, and will propose several novel experimental probes to unveil the topological superfluid state.


February 5
Gang Cao, University of Colorado at Boulder

The Power of Strong Spin-Orbit Interactions: Challenges and Opportunities in Iridates

Effects of spin-orbit interactions in condensed matter are an important and rapidly evolving topic. Strong competition between spin-orbit, on-site Coulomb and crystalline electric field interactions in iridates drives exotic quantum states that are unique to this group of materials. This colloquium offers a brief review of current experimental studies of iridates [1] and emphasize discrepancies between experimental confirmation and theoretical proposals that address superconducting, topological and quantum spin liquid phases. It then reports our most recent study on electrical-current controlled behavior in iridates [2]. Electrical control of structural and physical properties is a long-sought, but elusive goal of contemporary science and technology. This work demonstrates that a combination of strong spin-orbit interactions and a canted antiferromagnetic Mott state is sufficient to attain that goal and points the way to novel possibilities for functional materials and devices.

References:
1. "The Challenge of Spin-Orbit-Tuned Ground-States in the Iridates: A Key Issues Review", Reports on Progress in Physics (forthcoming), Gang Cao and P. Schlottmann http://arxiv.org/abs/1704.06007
2. "Electrical Control of Structural and Physical Properties via Spin-Orbit Interactions in Sr2IrO4", G. Cao, J. Terzic, H. D. Zhao, H. Zheng, Peter Riseborough, L. E. DeLong, Phys. Rev. Lett. 120, 017201 (2018); DOI: https://doi.org/10.1103/PhysRevLett.120.017201; Editor’s Suggestion


April 16
H.L. Dodds, IBM Professor, Emeritus, UT Nuclear Engineering

Energy Choices and Consequences

With the world's population increasing from seven billion currently to approximately nine billion by the year 2040, achieving a healthy lifestyle for all people on earth will depend, in part, on the availability of affordable energy, especially electricity. This presentation focuses on the various options for producing and using electricity, and the consequences associated with each option. The options include fossil, renewables, and nuclear. All energy options are needed, but some options may be better than others when compared in the following five subject areas: economics, environmental effects, public health and safety, sustainability, and politics. This presentation briefly compares the three options in each of the five areas.


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