Current Seminars and Colloquia

Article Index

Spring 2021

Physics department colloquia in 2021 via Zoom

PHYSICS Colloquium

April 22 2021, Thursday, 3:30 pm CST

Via Zoom (contact Physics Dept. for link) 

dec2019Dr. Djuna Croon

IPPP, Durham University, United Kingdom

 

 

 

Black hole archaeology with gravitational waves

Black holes are the mysterious remnants of heavy stars. Through gravitational waves, we can study the properties of entire populations of black holes for the first time. In this talk I will demonstrate how such studies can be used to learn about particle and nuclear physics in stars. The key insight is that due to an instability in stellar cores, a wide range of initial stellar masses leaves no black hole remnant. The unpopulated space in the stellar graveyard is known as the black hole mass gap (BHMG). The effects of new physics can dramatically alter the late stages of stellar evolution, resulting in shifts of the BHMG. I will give several examples, and demonstrate how these predictions can be tested using the growing catalogue of gravitational wave observations.  

PHYSICS Colloquium

Being rescheduled for Fall Semester (in-person!)

iski erin 10122017Dr. Erin Iski  
Chemistry and Biochemistry
University of Tulsa

PHYSICS Colloquium

April 7 2021, Wednesday, 4:00 pm CST

Via Zoom (contact Physics Dept. for link) 

Darling IME 900pxDr. Seth Darling  

University of Chicago and Argonne National Laboratory

 

 

 

Water technologies by interface engineering

Driven by climate change, population growth, development, urbanization, and other factors, water crises represent one of the greatest global risks in the coming decades.  Advances in materials represent a powerful tool to address many of these challenges.  Understanding—and ultimately controlling—interfaces between materials and water are pivotal.  In this presentation, Dr. Darling will lay out the challenges and present several examples of work in his group based on materials engineering strategies for addressing applications in water.  In each instance, manipulation of interfacial properties provides novel functionality, ranging from selective transport to energy transduction to pollution mitigation.

PHYSICS Colloquium

March 31 2021, Wednesday, 3:30 pm CST

Via Zoom (contact Physics Dept. for link) 

Midhat Farooq 1Dr. Midhat Farooq

APS Career Program Manager

 

 

 

 

Physics Careers: the Myths, the Data, and Tips for Success

Physics degree holders acquire a diverse set of skills and their training makes them extremely employable in the private sector. While physics programs are well-equipped to give students resources for and a glimpse into the life of an academic career, they often lack the tools to provide the necessary exposure and preparation for other career paths. In this talk, I will go over some data regarding career trajectories of physics degree holders while breaking down common myths and misperceptions. Next, I will provide some guidance on steps students can take to better inform their choices as they pursue various career paths, as well as go over information and tools that advisors can use to mentor students.  

PHYSICS Colloquium

March 24 2021, Wednesday, 3:30 pm CST

Via Zoom (contact Physics Dept. for link) 

Kwiat

Dr. Paul Kwiat  

University of Illinois Urbana-Champaign
Urbana, Illinois 







Advanced Quantum Communication: Where do we go from here?

It is now well understood that quantum mechanics can enable otherwise impossible feats in the processing and communicating of information. For example, quantum cryptography enables provably secure encryption, even as the looming reality of quantum computers threatens our existing methods of encryption.  To help bridge the gap to an eventual global multi-node quantum network, we are pursuing airborne and satellite-based free-space quantum communication. Free-space platforms may be easily moved/reoriented to target new nodes, and an agile, reconfigurable system -- we are implementing a multi-rotor drone-based system  -- could enable quantum cryptography in applications prohibited by current approaches, such as temporary networks in seaborne, urban, or even battlefield situations. At longer scale, we are pursuing a quantum link from space to earth, which could be used to link terrestrial local quantum networks. One option is to use hyperentanglement to enable several advanced quantum communication protocols, including “blind” quantum computing and “superdense" teleportation.

PHYSICS Colloquium

March 18 2021, Thursday, 3:30 pm CST

Via Zoom (contact Physics Dept. for link) 

GB Lemos 300Dr. Gabriela B. Lemos 

Instituto de Fisica
Universidade Federal do Rio de Janeiro
Brazil





 

 
Imaging and other applications of induced coherence without induced emission

In 1991 Zou, Wang and Mandel introduced the mind-boggling concept of induced coherence without induced emission with an experiment using photon pairs created in a superposition of two spatially separate sources. Based on this experiment, in 2014 we created a novel and counterintuitive quantum imaging scheme where the image of an object is obtained in a light beam which never interacts with the object. The light beam used to illuminate the object is not detected at all. Since then, my collaborators and I have explored various applications of induced coherence without induced emission, shedding light on curious and useful quantum phenomena.

PHYSICS Colloquium

March 11 2021, Thursday, 3:30 pm CST

Via Zoom (contact Physics Dept. for link) 

ellisDr. John Ellis  

King's College London & CERN







Grand Unified Theories and Proton Decay

Given the successes of the Standard Model of particle physics, theorists have proposed models that would unify all the particle interactions, possibly including gravity in the context of string theory. Such Grand Unified Theories (GUTs) have related successfully the varying strengths of particle interactions, and predicted the mass of the bottom quark before its discovery. They also suggested that neutrinos should have small masses and oscillate, as discovered by an experiment designed to look for the decays of protons. These decays have but not yet been seen, despite being expected on general grounds and a key prediction of GUTs. A new generation of underground neutrino experiments will have unprecedented capabilities to detect decays of protons. It would be ironic if they finally observe proton decay!

PHYSICS Colloquium

March 3 2021, Wednesday, 3:30 pm CST  
(Talk will be followed by discussion for how to get involved.)

Via Zoom (contact Physics Dept. for link) 

Alan Robock 275x317Dr. Alan Robock   

Rutgers University




 
 

Climatic and Humanitarian Impacts of Nuclear War

A nuclear war between any two nations, such as India and Pakistan, with each country using 50 Hiroshima-sized atom bombs as airbursts on urban areas, could inject 5 Tg of soot from the resulting fires into the stratosphere, so much smoke that the resulting climate change would be unprecedented in recorded human history.  Our climate model simulations find that the smoke would absorb sunlight, making it dark, cold, and dry at Earth’s surface and produce global-scale ozone depletion, with enhanced ultraviolet radiation reaching the surface.  The changes in temperature, precipitation, and sunlight from the climate model simulations, applied to crop models show that these perturbations would reduce global agricultural production of the major food crops for a decade. Since India and Pakistan now have more nuclear weapons with larger yields, and their cities are larger, even a war between them could produce emissions of 27 or even 47 Tg of soot.
    My current research project, being conducted jointly with scientists from the University of Colorado, Columbia University, and the National Center for Atmospheric Research, is examining in detail, with city firestorm and global climate models, various possible scenarios of nuclear war and their impacts on agriculture and the world food supply.  Using six crop models we have simulated the global impacts on the major cereals for the 5 Tg case.  The impact of the nuclear war simulated here, using much less than 1% of the global nuclear arsenal, could sentence a billion people now living marginal existences to starvation.  By year 5, maize and wheat availability would decrease by 13% globally and by more than 20% in 71 countries with a cumulative population of 1.3 billion people.  In view of increasing instability in South Asia, this study shows that a regional conflict using <1% of the worldwide nuclear arsenal could have adverse consequences for global food security unmatched in modern history. The greatest nuclear threat still comes from the United States and Russia.  Even the reduced arsenals that remain in 2020 due to the New START Treaty threaten the world with nuclear winter.  The world as we know it could end any day as a result of an accidental nuclear war between the United States and Russia.  With temperatures plunging below freezing, crops would die and massive starvation could kill most of humanity.
    As a result of international negotiations pushed by civil society led by the International Campaign to Abolish Nuclear Weapons (ICAN), and referencing our work, the United Nations passed a Treaty to Ban Nuclear Weapons on July 7, 2017.  On December 10, 2017, ICAN accepted the Nobel Peace Prize “for its work to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons and for its ground-breaking efforts to achieve a treaty-based prohibition of such weapons.”  Will humanity now pressure the United States and the other eight nuclear nations to sign this treaty?  The Physicists Coalition for Nuclear Threat Reduction is working to make that happen.

PHYSICS Colloquium

February 25 2021, Thursday, 3:30 pm CST

Via Zoom (contact Physics Dept. for link) 

ajitDr. Ajit Srivastava   

Institue of Physics, Bhubaneswar

 

 

 

 

Investigating Cosmic string theories with Liquid Crystal Experiments

Spontaneous symmetry breaking plays crucial role in elementary particle physics, leading to the existence of Higgs boson, to exotic topological objects like cosmic strings and magnetic monopoles in the universe. Analogs of such topological objects in condensed matter are flux tubes in superconductors, vortices in superfluids, and hedgehogs and strings in liquid crystals. Liquid crystals provide a very convenient system where such topological defects can be experimentally studied in a variety of physical conditions. We will discuss how the observations of string formation in a liquid crystal system can be used to test theories of cosmic string formation in the early universe. Main focus of these investigations is on various universal aspects of defect formation with which one can establish rigorous quantitative correspondence between these condensed matter experiments and elementary particle physics models of the early universe.

PHYSICS Colloquium

February 18 2021, Thursday, 1:00 pm CST

Via Zoom (contact Physics Dept. for link) 

c690ff864b49d85302e4066afa9cbac4Dr. Joe Smerdon

University of Central Lancashire

 

 

 

 

Adsorption of fullerene and pentacene on Cu(111) 

 
Pentacene and fullerene are archetypal molecules for adsorption studies on surfaces.  The first bond-resolved SPM image was of a pentacene molecule and fullerene, the famous soccerball of carbon atoms, needs little introduction.
    They are archetypal in several ways, however.  Pentacene is the organic donor (p-type) molecule with the highest carrier mobility.  It is also high-aspect ratio (~5:1:0) so is useful for geometrical studies of one-dimensional (rod-shaped) particles.  Fullerene is an isotropic (0-dimensional) organic acceptor (n-type) molecule and one of its derivatives (PCBM) is currently the best performing organic acceptor.  These molecules are therefore useful for investigations of adsorption geometries and of electronic structure and function.
    I will discuss the self-assembly behaviour of pentacene and fullerene on Cu(111), which (along with Au(111)) is probably the most archetypal surface for molecular adsorption.  In addition to describing how the molecules behave separately, I will describe how they behave in concert.  Starting with a collection of the most exhaustively studied and common components in surface science - C60, pentacene and copper - I will describe how one will encounter degenerate ordering, chirality and one of the best performing nanoscale molecular diodes yet discovered.

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Image: One of the co-adsorption structures of pentacene and fullerene on Cu(111). Scanning tunneling micrograph, 15 nm x 15 nm.

PHYSICS Colloquium

February 11 2021, Thursday, 4:00 pm CST

Via Zoom (contact Physics Dept. for link) 

CaoY 201909 ANL MSD low res 0Dr. Yue Cao

Argonne National Lab

 




‘Normal-state’ nematicity in a spin-orbit coupled Mott insulator

Nematicity – unidirectional order that breaks the rotation symmetry of the underlying lattice – appears to be ubiquitous among different families of high Tc cuprates and Fe-based superconductors. All known cases involve metallic materials or doped Mott insulators, i.e. systems with itinerant carriers, leading to theoretical descriptions centering around the Fermi surface topology. Here we discuss nematic order in the spin-orbit-coupled Mott insulator Sr2IrO4. The transverse charge susceptibility is two-fold symmetric relative to the Ir-O-Ir bond direction at room temperature above the Neel antiferromagnetic order. Close structural surveys using electron, neutron and X-ray diffraction and phonon measurements using inelastic X-ray scattering show the lattice maintains tetragonal symmetry within our experimental resolution, suggesting an electronic origin of the newly observed order. The nematicity and the lattice degree of freedom both exhibit an anomaly around the onset of the long-range magnetism, highlight the orbital and charge nature of the pseudospin, as well as the intricate interaction between the quasi-2D magnetic layers. We will discuss the implications of our discovery, both in the realm of iridates and more broadly regarding doped Mott insulators. 

PHYSICS Colloquium

February 4 2021, Thursday, 4:00 pm CST

Via Zoom (contact Physics Dept. for link) 

ruda bioDr. Harry E. Ruda

University of Toronto

 

 

 

 

 

A superficial tale: How semiconductor nanowires offer a remarkable platform for nanoelectronics and sensing

The first foray into semiconductor micron-scale ‘whiskers’ came from work by Wagner and Ellis in 1964, only to applied in the late 1990’s to realise nanowires with diameters of tens of nanometers. With the possibility of strong confinement in two dimensions these structures appear to be ideal vehicles for 1d physics and devices. However, surface related phenomena can provide a curse or opportunity in this quest - the latter is the focus of this presentation. Here, I focus on the opportunities in a few areas including ballistic conductance, random telegraph noise, and scattering from individual surface charges. Harnessing these phenomena can enable a host of new opportunities including making inroads in the quest to tame the elusive Majorana Fermion, in ultra-sensitive elevated temperature single charge electrometry and in single molecule level sensing.

PHYSICS Colloquium

January 28 2021, Thursday, 4:00 pm CST

Via Zoom (contact Physics Dept. for link) 

Picture1Dr. Sunil Chirayath   

Center for Nuclear Security Science and Policy Initiatives, Texas A&M University





 

Role of Nuclear Security Education in the Peaceful Uses of Nuclear Energy

Electricity production using nuclear technology has historically been one of the largest contributors of carbon-free electricity world-wide, highlighting its immense potential to be a factor in decarbonization efforts. Nuclear power plants can provide stable base load power while operating in the load-follow mode, which makes nuclear power a viable candidate to be considered as a complimentary source in the energy mix while the prominence of variable renewables rises. The challenge is to deploy economically competitive advanced nuclear reactor designs that can be built and operated safely and securely and also address the nuclear waste issue. In this colloquium, I will present the role of nuclear security and nonproliferation in the operation of nuclear power plants and the associated nuclear fuel cycle facilities by discussing its basic principles and major components. Further, I will provide a couple of examples of research conducted in this area and the curriculum followed at Texas A&M University to emphasize the needs for developing a competent and multi-disciplinary workforce to support the nuclear security and nonproliferation mission.

PHYSICS Colloquium

January 21 2021, Thursday, 4:00 pm CST

Via Zoom (contact Physics Dept. for link)

speaker image

Dr. Adina Luican-Mayer 
University of Ottawa

 

 

 

 

Quantum materials at the atomic scale

Understanding and controlling the properties of 2D materials to our advantage can be contemplated with the development of experimental tools to probe and manipulate electrons and their interactions at the atomic scale. In this talk, I will present scanning tunnelling microscopy and spectroscopy experiments aimed at: elucidating the nature of atomic-scale defects in 2D materials [1], visualizing moiré patterns between crystals with different symmetries [2] and imaging surface and edge states in a magnetic topological system. Moreover, I will discuss how we leverage our expertise in probing and engineering electronic states at surfaces of 2D materials to further the development of graphene-based gas sensors [3] and gated quantum dot circuits based on 2D semiconductors [4]. 

[1] Plumadore et al., PRB, (2020) 
[2] Plumadore et al., Journal of Applied Physics, (2020)
[3] Rautela et al., ACS Applied Materials & Interfaces (2020) ​
[4] Boddison-Chouinard, Appl. Phys. Lett., (2019)

HEP Seminar

January 21 2021, Thursday, 12:00 pm CST
More details: osuhep.okstate.edu   

Roshan Mammen Abraham

Oklahoma State University

NC Neutrino interactions at FASERnu

OKPVRI Annual Meeting & Symposium

January 15 2021
https://okpvri.okstate.edu

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