Current Seminars and Colloquia

Article Index

Spring 2022

Physics Department Colloquia and Seminars in 2022


PHYSICS Colloquium

April 21 2022, Thursday, 3:30 pm CST
Physical Sciences 110

Walton imageDr. Donnell Walton 
Director of the Corning Technology Center in Silicon Valley

 

 

 

 

The industrial lab as an environment to learn, know and do science

Corning Incorporated has a 170-year history of life-changing innovations--starting with railroad signal lenses and the mass production of Edison's light bulb. After a brief overview of our history of inventions and the underlying science, I'll discuss some of the hottest current areas in applied materials science and physics research along with some emerging applications. I'll close with some professional reflections from my quarter century of experience as an industrial physicist performing and leading transdisciplinary research.


High Energy Seminar

April 07, 2022, Thursday, 12:30 pm CST
147 Physical Sciences

Sudip Jana
Max Planck Institute
Heidelberg

Oklahoma State University Alum

 Sudip Jana

 TITLE: Light from Neutrinos

Abstract: Neutrinos are one of the most abundant of all known particles in the Universe, but yet the least understood ones. In the Standard Model, neutrinos are massless and interact only via the weak force. However, the discovery of neutrino oscillations implies that neutrinos are massive and mixed. Therefore, the Standard Model must be extended to account for the tiny neutrino masses. In these extensions, neutrinos also acquire electromagnetic properties through quantum loops effects. The theoretical and experimental investigation of neutrino electromagnetic interactions can serve as a powerful tool in searching for the fundamental theory behind the neutrino mass generation mechanism. We show that the models that induce neutrino magnetic moments while maintaining their small masses naturally also predict observable shifts in the charged lepton anomalous magnetic moment. This shift is of the right magnitude to be consistent with the Brookhaven measurement as well as the recent Fermilab measurement of the muon g-2. This points out the direct correlation between the magnetic moment of SM charged lepton and neutral lepton (neutrino) by showing that the measurement of muon g-2 by the Fermilab experiment can be an in-direct and novel test of the neutrino magnetic-moment hypothesis,  which can be as sensitive as other ongoing-neutrino/dark matter experiments. Results will be discussed.


PHYSICS Colloquium

March 22, 2022, Tuesday, 3:30 pm CST
via Zoom

vasdekis

Dr. Andreas Vasdekis
University of Idaho

 

 

 

 

Microbial Metabolic Noise

From the very first bioimaging experiments, it became clear that no two genetically identical cells “look” the same in size and content. This phenomenon is generally referred to as ‘noise’ and is now better understood, both in the context of how single cells shape the behavior of a population, and its physical origins [1].

In this talk, I will present our findings of how noise impacts microbial metabolism, with a focus on cell growth and lipid production [2-5]. In particular, I will detail our recent discovery of the asymmetric partitioning of molecular content between two dividing cells, and the homeostasis of intracellular molecular crowding [5].

Further, I will summarize our optical microscopy research on the metabolic imaging of single, living cells that made these findings possible. Here, my focus will specifically be on quantitative mass microscopy, and the imaging of metabolic and gene expression dynamics with minimal phototoxicity and high throughput rates [6-8].

References:

[1] A. E. Vasdekis, A. Singh, Wiley Systems Biology and Medicine, 10.1002/wsbm.1512 (2020).

[2] A.E. Vasdekis, H. Alanazi, A. M. Silverman, C. J. Williams, A. J. Canul, J. B. Cliff, A. C. Dohnalkova, G. Stephanopoulos, Nature Communications 10, 848 (2019).

[3] A. E. Vasdekis, A. M. Silverman, G. Stephanopoulos, Scientific Reports 5, 17689 (2015).

[4] A. E. Vasdekis, A. M. Silverman, G. Stephanopoulos, PLOS ONE 12, e0168889 (2017).

[5] S. Nemati, A. Singh, S. D. Dhuey, A. McDonald, D. M. Weinreich, A. E. Vasdekis, bioRxiv (2021).

[6] N. R. Subedi, P. S. Jung, E. L. Bredeweg, S. Nemati, S. E. Baker, D. N. Christodoulides, A. E. Vasdekis, Scientific Reports 10, 20150 (2020).

[7] N. R. Subedi, S. Yaraghi, P. S. Jung, G. Kukal, A. G. McDonald, D. N. Christodoulides, A. E. Vasdekis, Optics Express 29, 31941 (2021).

[8] T. Sanchez, N. R. Subedi, C. Thompson, L. Sheneman, A. E. Vasdekis, ACS Photonics 8, 2876 (2021).


PHYSICS Colloquium

March 10 2022, Thursday, 3:30 pm CST
via Zoom

xueda wen photoDr. Xueda Wen
Harvard University

 

 

 

Time-dependent Driven Quantum Critical Systems

Non-equilibrium phenomena in many-body quantum systems are cutting-edge research topics in modern physics. One central question is how to identify and characterize the emergent dynamical phases in the non-equilibrium process. In this talk, I will introduce a family of exactly solvable time-dependent driven quantum many-body systems at the critical point. Not only being exactly solvable, these examples exhibit a rich variety of dynamical phenomena, such as a dynamical phase transition between heating and non-heating phases during the time evolution. When subjected to periodic/quasi-periodic/random drivings, I will show how the emergent dynamical phases are related to the properties of wavefunctions in crystals/quasi-crystals/Anderson localizations that we have learnt in our undergraduate physics. Many interesting future directions will be introduced in the end.


PHYSICS Colloquium

March 8 2022, Tuesday, 3:30 pm CST
via Zoom

Susanta Portrait Shortenedv2Dr. Susanta K. Sarkar
Colorado School of Mines

 

 

 

Looking at Life Through Randomness

One-third of the talk: Randomness is ubiquitous around us, and we often repeat experiments and average with an assumption that the underlying randomness is Gaussian-distributed. I will introduce the Poisson process, a type of randomness that has a constant probability of occurring in each spatial or temporal step. Many natural processes, including radioactive decay, photons from a laser, biomolecular interactions, chocolate chips in cookies, cell distribution in vitro tissue model, and so on, can be either described or approximated as a single or a chain of Poisson processes. We have used the Poisson process approach to understand the relationship between random protein dynamics and activity, which I will present in the context of matrix metalloproteases (MMPs).

Two-thirds of the talk: MMPs, a family of 23-member enzymes, interact with and degrade many biomolecules in the human body, and as such, MMPs have diverse functions and are directly or indirectly related to most human diseases. Scientists have tried to target MMP functions using drugs for treating diseases. For example, we need to stop collagen degradation by MMPs to prevent cancer metastasis. However, drugs that prevent MMPs from degrading collagen also inhibit other useful functions of MMPs, leading to adverse side effects and failures of clinical trials. We hypothesize that if we understand how MMPs interact with different biomolecules (substrates), not just collagen, we may change one function of MMP without affecting its other functions. I will share measurements and simulations of MMP dynamics at the single molecule level that suggest each substrate has its unique signature in MMP at the catalytic and distant allosteric sites. We have identified allosteric sites or "fingerprints" of several substrates, including collagen fibril, fibrin, alpha-synuclein aggregates, and amyloid-beta aggregates. Screening drugs against substrate-specific allosteric sites enables a better selection of drugs based on single molecule insights.


PHYSICS Colloquium

March 3 2022, Thursday, 3:30 pm CST
via Zoom

Headshot SCDr. Sayan Choudhury
University of Pittsburgh

 

 

 

Non-equilibrium Dynamics of Synthetic Quantum Matter

In recent years, rapid advances in the development of quantum technologies have led to the possibility of creating and manipulating large-scale “synthetic quantum matter”. These unique many-body platforms synthesized from ultracold atoms, molecules, ions, and photons provide a powerful and versatile route to elucidate quantum phenomena that may be difficult (or even impossible) to realize elsewhere in nature. In this colloquium, I will present some of our recent work on understanding the non-equilibrium properties of these systems. In the first part of the talk,  I will propose a route to realize a discrete time crystal in a periodically driven quantum system. A time crystal is a fascinating non-equilibrium phase of matter that exhibits spontaneous time-translation-symmetry breaking. I will demonstrate that a many-body interference mechanism can be harnessed to create an eternal time crystal with global "all-to-all" interactions. In the second part of the talk, I will describe quantum information scrambling in a chaotic spin-chain with competing short and long-range interactions. I will argue that this system can exhibit fast scrambling, thereby providing a route to probe aspects of quantum gravity in near-term experiments.  I will then briefly describe the kaleidoscope of quantum phases that emerge in this system and conclude with a a brief overview of future research directions.


PHYSICS Colloquium

March 1 2022, Tuesday, 3:30 pm CST
via Zoom

victor CDr. Victor Colussi
University of Trento

 

 

 

Exploring Quantum Fluids with Ultracold Atoms

Quantum fluids display such spectacular macroscopic quantum effects as superconductivity and superfluidity.  Yet underlying these phenomena is a deceptively simple question: What happens when particles cease to become separate objects and begin to feel their surrounding neighbors?  Understanding this transformation in the presence of strong correlations has remained a difficult question across many branches of physics.  Recently, ultracold atomic gases have emerged as a versatile platform for the applied quantum simulation of these systems.  I will describe on-going efforts using ultracold atomic Fermi superfluids to search for the condensed matter version of the Higgs mode. I will also highlight how the discovery of counterintuitive Borromean few-body states in ultracold atomic Bose gases has opened up a new frontier in the study of strongly correlated quantum fluids.


PHYSICS Colloquium

February 24 2022, Thursday, 3:30 pm CST
via Zoom

sundar bhuvanesh webDr. Bhuvanesh Sundar
JILA, University of Colorado, Boulder

 

 

 

 

New frontiers for variational quantum algorithms: quantum entanglement and information scrambling

Variational quantum algorithms are rapidly emerging as a new paradigm for performing computations on noisy intermediate-scale quantum devices towards various applications. Harnessing the power of both classical and quantum computers, these algorithms implement parameterized quantum circuits that are trained by a classical optimizer, to produce a desired quantum state or solution to a classical optimization problem. They have been successfully used to solve optimization problems arising in in mathematics, computer science, and many-body physics. In this talk, I will present two novel applications of variational techniques. In the first application, I will use variational techniques to learn the entanglement Hamiltonian for subsystems in a strongly correlated many-body wavefunction, which is crucial to characterizing entanglement in the quantum many-body state. I will show that the technique efficiently learns the entanglement Hamiltonian, and produces results consistent with predictions from field theory. In the second application, I will use variational state preparation to probe quantum information scrambling in a many-body system. I will describe experiments which prepared the thermofield double state for spin models at finite temperature, and made the first experimental measurement of out-of-time-ordered correlators at finite temperature. I will conclude by discussing new and promising avenues for variational quantum algorithms.


PHYSICS Colloquium

February 22 2022, Tuesday, 3:30 pm CST
via Zoom

GuptaDr. Sharad Gupta
IIT Indore, India

 

 

 

 

Near-Infrared Optical Imaging, Diagnosis, and Therapeutics

Biological tissue is an optically turbid medium with a dominant scattering and absorption in the visible wavelength range. However, the tissue is relatively transparent with minimal absorption and scattering from ~650 nm to ~950 nm. This near-infrared (NIR) wavelength window could be used for extracting molecular information for diagnostic applications and therapeutics. The use of a NIR exogenous fluorescence contrast agent enables us to visualize deeply buried inhomogeneities in tissue. We have developed optically active biocompatible and biodegradable polymeric and protein-based nanoparticles for near-infrared fluorescence imaging. Due to significant absorption in NIR wavelength, the nanoparticles are used for photothermal therapy applications. In the NIR window, the less scattering, low endogenous absorption, and almost zero tissue autofluorescence improved molecular characterization. Recently, we have developed a Raman signal enhancing technique, nano-trap enhanced Raman spectroscopy, for bio-fluid analysis. For this, samples were excited with a NIR laser (785 nm). This technique has increased the range of detection of diagnostically relevant biomolecules. Therefore, the tissue transparent NIR wavelength range provides an exciting option for rapid disease diagnosis and efficient therapeutics.


PHYSICS Colloquium

February 17 2022, Thursday, 3:30 pm CST
via Zoom

thumbnail image001Dr. Thomas Bilitewski
JILA, University of Colorado, Boulder

 

 

 

 

Exploring Long Range Dipolar Interactions: From collective dipolar spin dynamics and layer exchange to light-mediated interactions and Pauli-Blocking

In this talk I will discuss recent theoretical and experimental work exploring the dynamics of dipolar quantum systems for quantum sensing, simulation and discovery. I will begin by discussing our theoretical proposal using dipolar molecules confined in two dimensions as a platform for robust generation of entangled states, useful for quantum metrology and quantum enhanced field sensing. To this end I will discuss how we can understand the dynamics of the dipolar quantum gas in terms of a long-range highly-collective spin model in mode-space. The highly collective nature of the resulting model allows us to overcome challenges of losses inherent to dipolar molecules in bulk systems, and results in dynamics robust to dephasing and thermal noise in the degenerate quantum degenerate regime. I will then continue by presenting recent experimental work developing the tool box required to prepare and probe molecules in layer geometries, and our theoretical work on understanding the spin dynamics resulting from dipolar exchange. The dipolar interaction induced spin exchange between adjacent layers enables strong losses within layers, allowing to probe the coherent exchange process via the measurement of the molecular loss. I will discuss how in presence of electric field gradients the spin dynamics can only be understood in terms of inelastic collisions between molecules in adjacent layers, converting motional into internal energy during the exchange process. This part highlights how motional dynamics and spin dynamics are intertwined in this system. Finally I will discuss the interplay of light-mediated dipolar interactions, atomic motion and quantum statistics in the problem of observing Pauli-blocking enhanced life-times of optically excited states in a 2D Fermi gas. I will present a theoretical framework developed to account for the main cooperative effects due to the dipolar interactions mediated by the exchange of photons, and the statistics of Fermions enabling us to identify a favourable regime in which Pauli-blocking can be clearly distinguished from cooperative effects, and present experimental observations in qualitative agreement with our theoretical predictions.

 

References:  PRL 126, 113401, arXiv:2112.13423, arXiv:2108.02819


PHYSICS Colloquium

January 20 2022, Thursday, 3:30 pm CST
Physical Sciences 110

TischlerDr. Joseph G. Tischler 
Homer L. Dodge Department of Physics and Astronomy
University of Oklahoma

 

 

 

 

3D Printed Infrared Metamaterials

Intense research on two-photon polymerization (2PP) processes has led to the development of sophisticated commercial apparatus capable of producing arbitrary 3D polymer scaffolds with spatial resolutions as high as 170nm. Generally speaking, these polymer-based constructs do not interact with photons due to their low conductivity and low dielectric constants. Therefore, they do not make good optical metamaterials by themselves; however, metals and materials with high dielectric constants such as polar dielectrics (e.g., Si, hBN and SiC) do. In this work we produced novel optical metamaterials combining 2PP (or 3D printed) structures with e-beam evaporation, atomic layer deposition and/or reactive-ion etching. Furthermore, we compare optical measurements performed on these structures with full-wave electromagnetic simulations, demonstrating the strength of these fabrication methods for chiral/non-chiral structures suitable for applications such as SERS, SEIRA, light steering and subwavelength light focusing.

  


Fall 2021

Physics Department Colloquia and Seminars in 2021

PHYSICS Colloquium

September 16 2021, Thursday, 3:30 pm CST
Physical Sciences 110

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


 

 

 

Visualizing Nanoscale Surface Chemistry: From Ultra-High Vacuum to Electrochemical Environments

Scanning tunneling microscopy (STM) is a specialized technique that can be used to examine and study nanoscale surface chemistry due to its extreme resolution. The requirement of pristine molecular resolution of certain systems necessitates the use of low temperature, ultra-high vacuum STM (LT-UHV STM) during the initial characterization of the surfaces. Importantly, it is also possible to study the assembly of molecules and atoms with liquid and electrochemical STM (EC-STM) in an attempt to bridge the temperature and pressure gap of ultra-high vacuum studies and to take measurements under more realistic conditions. The first investigation focuses on the EC-STM study of five simple amino acids (L-Valine, L-threonine, L-Isoleucine, L-Phenylalanine, and L-Tyrosine) as well as two modifications of a single amino acid (L-Isoleucine Ethyl Ester and N-Boc-L-Isoleucine), and the means by which these molecules interact with a Au(111) surface. Using EC-STM under relevant experimental conditions, the amino acids were shown to have a considerable interaction with the underlying surface. In some cases, the amino acids trapped diffusing adatoms to form Au islands and in other cases, they assisted in the formation of magic gold fingers. Importantly, these findings have also been observed under UHV conditions, but this is the first demonstration of the correlation in situ and was controlled via an external applied potential. Additional studies examining the role that surface temperature played in formation of the adatom islands will also be discussed. By analyzing the results gathered via EC-STM at ambient conditions, fundamental insight can be gained into not only the behavior of these amino acids with varied side chains and the underlying surface, but also into the relevance of LT-UHV STM data as it compares to data taken in more realistic scenarios. In the second project, EC-STM was used to study the deposition of Ag on Au(111), which in the presence of chloride, formed an ultra-stable layer that was stable in air and to temperatures as high as 1,000 K. Interestingly, depending on the exact potential used to form the Ag layer, a different type of thermal stability was observed. This atomically thin and ultra-stable layer which was also resistant to oxidation may find applications in a variety of fields and select anti-corrosion applications.

.  

PHYSICS Colloquium

September 23 2021, Thursday, 3:30 pm CST
Physical Sciences 110

 Narducci 9 2021Dr. Francesco (Frank) Narducci

 Naval Postgraduate School
Associate Editor: Physical Review A, Physical Review Letters
 

 

 

Towards a T3 atom interferometer

In this talk, I will discuss a novel atom interferometer being developed at the Naval Postgraduate School. I will begin the talk by reviewing the theory of light pulse atom interferometers, concentrating on how the phase of the interferometer scales with the time between the atom optic pulses, T.  I will discuss the connection between the Lagrangian and Hamiltonian formulations for the calculation of the phase.  Next, I will demonstrate that the T2 scaling is due to a symmetry in the problem and that when the symmetry is broken, a T3 scaling appears (and in our geometry, the phase becomes purely dependent on a T3 term with no T2 terms). I will then turn to a discussion of an experimental implementation involving interferometry on magnetic transitions. The experiment is quite challenging and, although the signature T3 signal has so far eluded us, has provided many interesting features and physics which I will discuss.

PHYSICS Seminar

September 23 2021, Friday, 11:30 am CST
Physical Sciences 110

 Narducci 9 2021Dr. Francesco (Frank) Narducci

 Naval Postgraduate School
Associate Editor: Physical Review A, Physical Review Letters
 

 

 

Successfully Publishing in Physical Review Letters/The Physical Review

In this talk, I will discuss the general editorial process that leads to the publication (or rejection) of a manuscript submitted to Physical Review Letters/The Physical Review.  In a humorous atmosphere, I’ll present the “dos and don’ts” associated with publishing in the APS journals, starting from the initial submission to our appeals process. Statistics associated with the journal will be presented (but kept to a minimum!)  Finally, I’ll present some of our recent initiatives. Humorous stories will be injected throughout the talk.

PHYSICS Colloquium

September 30 2021, Thursday, 3:30 pm CST
Physical Sciences 110

 TomanekDr. David Tománek

 Michigan State University

 

 

 

 

Saving Humankind from Thirst

Whereas water itself is bountiful on Earth, much of it requires treatment to make it suitable for human consumption. Lack of potable water is currently the leading cause of death, ahead of any disease. Recent progress in fabricating nanostructured carbon allotropes may bring a long-awaited paradigm shift in designing membranes that would make efficient desalination of salt water using reverse osmosis and filtration of contaminated water possible. A previously unexplored membrane design [1] based on a unique layered assembly of carbon nanostructures including graphite oxide (GO), buckypaper consisting of carbon nanotubes, and a strong carbon fabric should provide high mechanical strength and thermal stability, resilience to harsh chemical cleaning agents and electrical conductivity, thus addressing major shortcomings of commercial reverse osmosis membranes. Microscopic insight into the critical permeation of water molecules in-between GO layers and across in-layer vacancy defects in graphitic carbon can be obtained using ab initio density functional theory calculations. Results of these computational studies elucidate the reason for selective rejection of solvated Na+ ions in an optimized layered all-carbon membrane.

[1] David Tománek and Andrii Kyrylchuk, Designing an All-Carbon Membrane for Water Desalination, Phys. Rev. Applied 12, 024054 (2019).

 

PHYSICS Colloquium

October 28 2021, Thursday, 3:30 pm CST
Via Zoom (contact Physics Department for link)

 

Dr. Phillip Ryan

Argonne National Laboratory

 

X-ray scattering and Electrical Measurements of Uniaxially Strained Single Crystals: Unconventional Superconductors and Single Phase Multiferroicity

In this presentation I will layout a brief overview of my research at the Advanced Photon Source (APS) with some recent results and describing a vision of what I plan for in the post source upgrade (APS-U) after 2023. The Magnetic Materials Group primarily serves the condensed matter community providing resonant hard x-ray magnetic scattering for single crystal systems, with a particular interest in epitaxial thin films (1). To drive our leading-edge scientific abilities, we continuously develop metrological tools which are made available to the community at large. Here, I will introduce recent developments to drive CMP scientific endeavors forward including low temperature uniaxial strain in a multimodal setup, and dynamic in-situ measurement configuration. Presenting recent results on single crystal unconventional superconducting pnictide systems BaFe2As2 parent compound we demonstrate in-situ uniaxial strain capability with commensurate electrical measurements (2-4).

In addition, I will present results from the intriguing, rare earth–titanate, EuTiO3. This material is an excellent platform to explore the interplay between spin, charge, and symmetry within a single system (5-7) and to expand the sample environment control capabilities that now serve a broader range of scientific interests. We try to untangle the magnetoelectric behavior in this single-phase system and in the process demonstrate a ‘giant’ ME cross-field control capability in the rare earth perovskite (5). In bulk form it is both antiferromagnetic and paraelectric. Both anti- and ferro- magnetic interactions are present between different nearest europium neighbors allowing for the notion of magnetic quantum criticality through a combination of doping or strain (8). Fortuitously, like SrTiO3, this system is also considered potentially quantum paraelectric or ‘incipient’ ferroelectric, this conjures the notion of bi-criticality or possibly the emergence of a coupled multiferroic quantum critical point (8).

  1. https://www.aps.anl.gov/Sector-6/6-ID-B-C/Publications
  2. Suppression of superconductivity by anisotropic strain near a nematic quantum critical point, P. Malinowski, et. al., Nature Physics, 1-5, (2020)
  3. The transport–structural correspondence across the nematic phase transition probed by elasto X-ray diffraction, JJ Sanchez, P Malinowski, J Mutch, J Liu, JW Kim, PJ Ryan, JH Chu, Nature Materials, 1-6 (2021)
  4. Strongly anisotropic antiferromagnetic coupling in EuFe2As2revealed by stress detwinning, Joshua J. Sanchez, Gilberto Fabbris, Yongseong Choi, Yue Shi, Paul Malinowski, Shashi Pandey, Jian Liu, I. I. Mazin, Jong-Woo Kim, Philip Ryan, and Jiun-Haw Chu, Phys. Rev. B 104, 104413 – Published 10 September 2021
  5. Reversible Control of Magnetic Interactions by Electric Field in a Single, P.J. Ryan et al, Nat. Commun. 4:1334, (2013)
  6.  Emergent Superstructural Dynamic Order due to Competing Antiferroelectric and Antiferrodistortive Instabilities in Bulk EuTiO3, J-W Kim, et al, Phys, Rev. Lett. 110, 027201 (2013).
  7. Multiferroic behavior in EuTiO3 films constrained by symmetry, P.J. Ryan, et. al., Phys. Rev. B 101, 180409 (2020)
  8. Multiferroic quantum criticality, Narayan, Andrés Cano, Alexander V. Balatsky, Nicola A. Spaldin, Nat. Mat. VOL 18 | MARCH 2019 | 223

 

PHYSICS Colloquium

November 4 2021, Thursday, 3:30 pm CST
Physical Sciences 110
marino crop

 Dr. Alberto Marino

 University of Oklahoma

 

 

 

 

Quantum-Enhanced Sensing with Light

There is a significant effort to take advantage of quantum resources, such as entanglement and superposition, to enhance measurements and devices in a way not possible with classical resources. This has led to the development of the emerging area of quantum technologies. Quantum optics will play a significant role in this so called “Second Quantum Revolution” due to the precise control and characterization that can be achieved with light. In this talk I will give an overview on the use of quantum states of light to enhance optical based sensors beyond the classical limit given by the shot noise. I will focus on our work on the interface between entangled twin beams of light and plasmonic sensors and show that a quantum-based sensitivity enhancement can be obtained. I will then describe the fundamental limits to the quantum enhancement that can be achieved. Finally, I will present our most recent work on the implementation of a parallel quantum-enhanced sensing approach.

 

PHYSICS Seminar: OKPVRI Plenary Symposium (hosted by Dr. Ian Sellers at OU)

November 16 2021, Tuesday, 10:00 am CST
Online via Zoom, Registration at: https://forms.gle/brETcQzVgtoJHgya7

Dr. Louise Hirst

University of Cambridge

 

Ultra-thin photovoltaics for space power applications

Space base services, such as real time imaging of the Earth’s surface and global communication networks are critical to many aspects of our modern lives. These services rely on satellite systems with payloads powered by solar cells. High efficiency III-V multijunction photovoltaic devices are standard for space power applications, in part due to their high performance and corresponding high specific power (W/kg), as well as their relative radiation tolerance, although increasingly other material systems are being considered for certain use cases. In this talk, the requirements for space power systems will be discussed along with key challenges driving innovation in the field. Ultra-thin geometries (active device thickness ~100 nm), offer many advantages for future satellite systems including flexible form factors for conformal system integration; reduced cost, materials usage and launch mass; and intrinsic radiation tolerance enabling new mission profiles in highly damaging environments. The challenges associated with moving to ultra-thin geometries will be discussed including the development of novel nanophotonic light management systems to obtain full solar absorption in ultra-thin films, along with the practical fabrication approaches for such systems.

PHYSICS Colloquium

November 11 2021, Thursday, 3:30 pm CST
Physical Sciences 110

 ManolissDr. Manolis Kargiantoulakis

 Fermilab
 
 

 

 

 

The Muon Anomalous Magnetic Moment: First results from the Fermilab Muon g-2 Experiment 

The Muon g − 2 Experiment at Fermilab has measured the anomalous magnetic moment of the muon to 460 parts-per-billion, based on data collected during the first physics run in 2018. The experiment determines the anomalous precession frequency of the muon spin inside the highly uniform and precisely measured magnetic field of our storage ring. Our result is consistent with the BNL measurement of the same quantity from nearly two decades ago. The experimental combination increases the tension with the Standard Model prediction, enhancing the significance of the discrepancy to 4.2σ. In this colloquium we will give an overview of the experimental measurement and discuss the status of the discrepancy, and why it could be very important for particle physics.

PHYSICS Colloquium

November 18 2021, Thursday, 3:30 pm CST
Online Via Zoom

 WuDr. Weida Wu

 Rutgers University
 
 

 

 

 

Berry Phase and Related Hall Effects

The Berry phase is the geometric phase of wavefunction in parameter space1. It underscores many interesting topological phenomena, especially various quantized or anomalous Hall effects1,2.  The quest for quantum Hall effect (QHE) without external magnetic field leads to the exciting development of quantum spin Hall effect (QSHE)3, the emergence of topological classification of band insulators4, and eventually the realization of quantum anomalous Hall effect (QAHE)5. In parallel to the fascinating evolution of Berry phase phenomena in the momentum space, there is also a real space counterpart, the topological Hall effect (THE) which is associated with non-coplanar spin textures with scalar spin chirality. As such, the THE provides a powerful probe of the ground state and low-energy excitations of magnetic metals. I will present our recent research progress on the QAHE and the THE in magnetic thin films using magnetic imaging technique with in-situ transport6–8.

References

  1. Xiao, D., Chang, M. C. & Niu, Q. Berry phase effects on electronic properties. Rev. Mod. Phys. 82, 1959–2007 (2010).
  2. Nagaosa, N., Sinova, J., Onoda, S., MacDonald, A. H. & Ong, N. P. Anomalous Hall effect. Rev. Mod. Phys. 82, 1539–1592 (2010).
  3. Kane, C. L. & Mele, E. J. Z2 topological order and the quantum spin Hall effect. Phys. Rev. Lett. 95, 146802 (2005).
  4. Fu, L., Kane, C. L. & Mele, E. J. Topological Insulators in Three Dimensions. Phys. Rev. Lett. 98, 106803 (2007).
  5. Chang, C.-Z. et al. Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator. Science 340, 167–170 (2013).
  6. Wang, W. et al. Direct evidence of ferromagnetism in a quantum anomalous Hall system. Nat. Phys. 14, 791–795 (2018).
  7. Wang, W. et al. Spin chirality fluctuation in two-dimensional ferromagnets with perpendicular magnetic anisotropy. Nat. Mater. 18, 1054–1059 (2019).
  8. Wang, W. et al. Chiral-Bubble-Induced Topological Hall Effect in Ferromagnetic Topological Insulator Heterostructures. Nano Lett. 21, 1108–1114 (2021).

Spring 2021

Physics department colloquia in 2021 via Zoom

PHYSICS Colloquium

May 5 2021, Thursday, 11:00 am CST  (Followed by Q&A with speaker: 11:45-12:15)

Via Zoom (contact Physics Dept. for link) 

unnamedDr. Andreas Vasdekis

University of Idaho

 

 

 

Stochastic Cellular Dynamics, Human Health Implications, and Related Methods

No two individual cells ever “look” the same, even if they share the same genes and grow under identical conditions. This unexpected phenomenon, generally termed cellular noise, emerges due to the stochastic nature of molecular-level interactions during protein production. In this talk I will introduce this phenomenon, its origins, and the related imaging, microfluidic, and deep learning methods that allow us to investigate it. I will then detail our recent findings of the effects of cellular noise on growth, lipid production, and response to antibiotics.  

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.

unnamed 2

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

image001-3.jpg

 


Fall 2020

CONDENSED MATTER PHYSICS Seminar 

Joseph Ngai

University of Texas-Arlington
Title: Electrically coupling multifunctional oxides to semiconductors through charge transfer
 

Semiconducting heterojunctions (e.g., pn-junction, isotype junctions, etc.) are the building blocks for virtually all electronic device technologies, ranging from solar cells to transistors. Such heterojunctions exhibit built-in electric fields that arise from a net transfer of itinerant charge between two electrically dissimilar semiconductors. Recent advancements have enabled charge transfer and built-in fields to be studied in heterojunctions between semiconductors and crystalline multifunctional oxides. The mixed covalent and ionic character of such hybrid heterojunctions could enable functionality that cannot be achieved using either material alone. After a brief introduction about multifunctional oxides, we will discuss our recent efforts in understanding charge transfer and the formation of built-in electric fields in SrNbxTi1-xO3-δ / Si heterojunctions. Magneto-transport measurements reveal charge transfer and the formation of a hole-gas in Si as Nb content in the oxide is varied. Hard x-ray photoelectron spectroscopy measurements allow us to map out built-in electric fields across heterojunctions by analyzing asymmetries in the core-level line shapes. Owing to the properties of oxides, hybrid heterojunctions exhibit behavior not found in conventional semiconducting heterojunctions, including the ability to tune band-alignments with doping. Such hybrid heterojunctions could address emerging challenges in energy harvesting and information technology.

November 20, 2020, 4:00PM

ONLINE (via Zoom: contact Dr. Mario Borunda, mario.borunda@okstate.edu if you would like to attend) 

CONDENSED MATTER PHYSICS Seminar 

Makhsud Saidaminov

University of Victoria, Department of Chemistry and Department of Electrical & Computer Engineering   
Title: 
Perovskite solar cells: why they perform well and degrade fast? 

Perovskite solar cells (PSCs) have recently reached a certified power conversion efficiency (PCE) of 25.2%, the fastest advance among all photovoltaic technologies. This has been enabled in significant part by combinatorial optimization of composition that now contains six or more components instead of three in the conventional perovskite. The key question is why perovskites need to be so much “contaminated” in order to perform well?

In this talk, I will discuss how mixing improves the efficiency and stability of perovskite solar cells. We found that the grains form with a gradient composition in mixed perovskite thin films, exhibiting a natural passivation layer on the surface of grains; this shields photogenerated carriers in solar cells [1]. I then show that alloyed perovskites have a remarkably reduced density of atomic vacancies, a major source of decomposition due to their high affinity for water and oxygen molecules [2]. Thus, alloying overcomes some of the problems that single cation/anion perovskites are prone to, such as formation of point defects in the crystal lattice and defective surfaces. 

[1] M. I Saidaminov, K. Williams, M. Wei, A. Johnston, R. Quintero-Bermudez, M. Vafaie, J. M. Pina, A. H. Proppe, Y. Hou, G. Walters, S. O. Kelley, W. A. Tisdale, E. H. Sargent. Multi-cation perovskites prevent carrier reflection from grain surfaces. Nature Materials, 19, 412 (2020).

[2] M. I. Saidaminov, J. Kim, A. Jain, R. Quintero-Bermudez, H. Tan, G. Long, F. Tan, A. Johnston, Y. Zhao, O. Voznyy, and E. H. Sargent. Suppression of atomic vacancies via incorporation of isovalent small ions to increase the stability of halide perovskite solar cells in ambient air. Nature Energy, 3, 648 (2018).

November 6, 2020, 4:00PM

ONLINE (via Zoom: contact Dr. Mario Borunda, mario.borunda@okstate.edu if you would like to attend) 

CONDENSED MATTER PHYSICS Seminar 

Brandon K. Durant

University of Oklahoma, Homer L. Dodge Department of Physics and Astronomy    
Title: Effects of Temperature and Proton Irradiation on Mixed Tin-Lead Halide Perovskites, Implications for Space Applications

Brandon K. Durant,* Hadi Afshari,* Vishal Yeddu,† Matthew T. Bamidele,† Bibhudutta Rout,‡ Do Young Kim,† Ian R. Sellers*
*Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK
†School of Materials Science and Engineering, Oklahoma State University, Tulsa, OK
‡Department of Physics, University of North Texas, Denton, TX
 

Mixed organic-inorganic halide perovskite solar cells (PSC’s) have garnered attention in recent years for their impressive solar to electrical power efficiency gains and potentially lower material and processing costs for optoelectronic applications. Here we investigate the properties of mixed formamidinium tin and methylammonium lead iodide (FASn)0.6(MAPb)0.4I3 perovskites which lower the lead content as well as the bandgap, making them more attractive for the absorber material in PSCs. In addition to terrestrial applications, PSCs are of interest to the space power markets for their low cost, low weight, adaptability to flexible architecture, and tolerance to high energy particle irradiation (mainly protons). Through current density-voltage (JV) characterization at lower temperatures, a barrier to photogenerated carrier extraction is evident and attributed to the changing bandgap of the absorber layer relative to the energy selective contacts in the device. Although the architecture used here hinders the performance at temperatures below 225 Kelvin, the tolerance to high energy protons is respectable compared to the current industry technologies.

October 16, 2020, 3:00PM

ONLINE (via Zoom: contact Dr. Mario Borunda, mario.borunda@okstate.edu if you would like to attend) 

CONDENSED MATTER PHYSICS Seminar 

TeYu Chien

University of Wyoming, Department of Physics and Astronomy    
Title: Electronic properties of novel materials - photovoltaic, 2D magnetic, and topological materials

Electronic properties, such as the electronic band structures and the density of states, of a material are at the center of understanding the physical properties. For examples, it is directly related to the optical properties, magnetic properties, and transport properties of the materials. Thus, the understanding of the electronic properties provide the fundamental basis of understanding the materials of interests. In this talk, I would like to share the results of our recent and on-going works focusing on three material categories: (1) photovoltaic materials (organic photovoltaic, and organometallic halide perovskite materials); (2) magnetic materials (CrBr3, Eu-Si nanowires, and EuO); and (3) topological materials (EuO, and 2M-WS2). Scanning tunneling microscopy and spectroscopy (STM/S) is the main tool used to provide the nm-scale understanding of the electronic properties.

September 17, 2020, 4:00PM
ONLINE (via Zoom: contact Dr. Mario Borunda, mario.borunda@okstate.edu if you would like to attend) 

 


Spring 2020

PHYSICS Colloquium

April 23, 2020 (POSTPONED due to COVID-19)
3:30PM

110 Physical Sciences

Mark Dean

 

Brookhaven National Lab

TBA

PHYSICS Colloquium

April 16, 2020  (POSTPONED due to COVID-19)
3:30PM

110 Physical Sciences

Matt Sieger

 

Oak Ridge National Lab

TBA

PHYSICS Colloquium

April 9, 2020  (POSTPONED due to COVID-19)
3:30PM

110 Physical Sciences

Frank Narducci

 

Naval Postgraduate School and PRA Editor

TBA

PHYSICS Colloquium

April 2, 2020  (POSTPONED due to COVID-19)
3:30PM

110 Physical Sciences

Alberto Marino

 

University of Oklahoma

TBA

PHYSICS Colloquium

March 12, 2020
3:30PM

110 Physical Sciences

Kong KC WEB

Kyongchul Kong
Department of Physics & Astronomy
University of Kansas

Title: Mathematics, Particle Physics and Machine Learning
Abstract: Our knowledge of the fundamental particles of nature and their interactions is summarized by the standard model of particle physics. Mathematically, the theory describes these forces and particles as the dynamics of elegant geometric objects called Lie groups and fiber bundles. Now advancing our understanding in this field has required experiments that operate at higher energies and intensities, which produce extremely large and information-rich data samples. The use of machine-learning techniques is revolutionizing how we interpret these data samples, greatly increasing the discovery potential of present and future experiments. In this talk, I will provide a brief overview of the standard model, and discuss how to search for new physics beyond the standard model with a specific example using neural networks

Journal Club Presentation

March 6, 200
3:30PM
147 Physical Sciences II

Brian Leininger
Oklahoma State University

Husimi projections on perturbation-induced scar states 


PHYSICS Colloquium

January 23, 2020Carlos Wagner
3:30PM

110 Physical Sciences

Carlos Wagner

 

Argonne National Laboratory and University of Chicago

PARTICLE PHYSICS :
LOOKING FOR ANSWERS TO FUNDAMENTAL QUESTIONS 

ABSTRACT: The Standard Model is one of the greatest scientific achievements of all time.
It is based on a quantum field theory that includes the electromagnetic interactions, the weak interactions associated with radioactive decays and the strong interactions associated with nuclear forces. It provides an excellent description of all laboratory experiments performed to date. However, there are a few important questions that this theory does not answer. One is why is the Universe composed of matter, with no visible anti-matter component. Another one is the nature of the Dark Matter, known to be necessary to explain the star rotation velocities and the structure of galaxies. There is also the question of how to incorporate (quantum) gravity within this description. Finally, there are a few unnatural features in this model that deserve explanation. Based on past successes, particle physicists today are concentrated on the answer to these fundamental questions. I will provide a review of the status of particle physics and of the ideas and experiments conceived to look for what lies beyond the Standard Model description. 

Biography

Dr. Carlos Wagner is the head of the Theory Group of the High Energy Physics Division at Argonne National Laboratory. He works as a Professor at the Enrico Fermi Institute and the Kavli Institute for Cosmological Physics at the University of Chicago. His area of research is phenomenology of particle physics, namely the study of the interactions of elementary particles, with a special emphasis on collider physics, Higgs physics, the theory of Dark Matter and the origin of the asymmetry between matter and anti-matter. He held postdoctoral positions at Purdue University, the Max Planck Institute in Munich and at the CERN Laboratory, where he also worked as a staff member between the years 1996 and 2000. Dr. Wagner is a Fellow of the American Physical Society and a recipient of a Humboldt Research Prize.

 

 


 

HIGH ENERGY PHYSICS Seminar 

Carlos Wagner

Argonne National Laboratory
Title: On the Higgs and Dark Matter


  Wagner 1 22 20

January 22, 2020, 4:00PM

Room: Physical Sciences 117, OSU / Nielsen Hall, Room 365, OU (online access)


PHYSICS Colloquium 

November 7, 2019
3:30PM
110 Physical Sciences

Pedro A. N. Machado

Fermi National Accelerator Laboratory

 

 

Neutrinos: Challenges and Opportunities.

Abstract: Neutrinos are one of the most abundant of all known particles in the universe, but yet the least understood ones. A rich neutrino physics program is underway, in the US and abroad, with the goal of significantly improving our knowledge of this sector. In this colloquium I will revisit what sort of physics we expect to learn from neutrinos, and the challenges that we will need to overcome in order to do so. I will highlight the big questions in neutrino physics and the impact of future experiments in answering these.


HIGH ENERGY PHYSICS Seminar 

November 7, 2019

1:30PM
109 Physical Sciences II, HEP Meeting Room

Has MiniBooNE observed the mechanism of neutrino masses? 

Dr. Pedro Machado, Fermilab

Abstract: In this talk I will entertain the possibility that the low energy excess observed by the MiniBooNE experiment is related to the mechanism of neutrino masses. I will review the MiniBooNE excess itself, present our proposal for a low scale neutrino mass model, and then show how these two could be connected.


PHYSICS Colloquium

October 31, 2019
3:30PM
110 Physical Sciences

Scarlett Ruppert

Department of Wellness
Seretean Wellness Center

Oklahoma State University

 

Discover wellness.

Abstract: Join Scarlett Ruppert, Coordinator of Employee Wellness, to learn about the multitude of fitness and wellness programs and services offered to OSU students, faculty, staff and family members. Discover the variety of options available to you right here on campus and learn how to live a healthier, happier, more productive life.

 

Bio: Scarlett Ruppert is the Coordinator for Employee Wellness at Oklahoma State University. She received her Bachelor’s degree in Exercise Science from Winthrop University in South Carolina. From there, she worked as an exercise physiologist before going back to school for her Master’s in Public Health at the University of North Carolina Greensboro. Scarlett has experience in personal training, group fitness, and swim instruction. She is also a National Board Certified Health and Wellness Coach where she helps individuals work toward their personal wellness goals including but not limited to physical activity, healthy eating, weight management, and mindfulness. She has several years of experience in educating a variety of populations on numerous health and wellness topics. Scarlett’s passions include educating individuals of the many benefits of adapting healthy lifestyle choices, and empowering those individuals to feel confident in making a sustainable change.


HIGH ENERGY PHYSICS SEMINAR 

October 24, 2019

1:30PM
155 Physical Sciences II, HEP Meeting Room

Probing leptonic scalars at the LHC

Dr. Yongchao Zhang, Washington University

Abstract: In this talk I will show how to probe a leptonic scalar which couples exclusively to the active neutrino at the LHC. Such a scalar can be produced at hadron colliders like LHC via vector boson fusion process and lead to same-sign dilepton, two forward jets and missing transverse energy. If the scalar mass is below GeV-scale, its couplings to neutrinos are stringently constrained by the low-energy high-precision data such as those from charged meson and charged lepton decays, W and Z data, neutrino beam experiments like MINOS, light dark matter searches in NA64, and IceCube limits on neutrino self-interactions. When the scalar mass is above the GeV-scale, the projected LHC sensitivity would surpass all existing bounds.


  

October 10th, 2019
3:30PM
110 Physical Sciences

Martin Centurion
Department of Physics and Astronomy
University of Nebraska

Ultrafast Diffractive Imaging of Molecules: Capturing molecular reactions with atomic resolution using electron pulses.

Abstract:Many processes in nature are driven by the conversion of light into chemical and mechanical energy at the level of single molecules. After absorbing a photon, chemical bonds can be broken and new bonds made, the structure of the molecule changes, and the extra energy appears in the form of vibrations (heat). These processes often take place on femtosecond timescales, and are thus hard to observe. In this talk, I will describe recent advances in our ability to capture these changes as they happen, on the relevant timescales and with atomic spatial resolution using ultrafast electron diffraction.  We will focus on a few exemplary reactions were we have imaged the motion of nuclear wavepackets during bond breaking and structural changes, and coherent vibrations that persist in the ground state of the reaction products.

 

Bio: Martin Centurion is the Susan J. Rosowski Associate Professor of Physics and Astronomy at the University of Nebraska – Lincoln. He received his BS in Physics with highest distinction from the University of Michigan – Ann Arbor in the year 2000, and his PhD from Caltech in 2005 in the group of Prof. Demetri Psaltis. He was a Postdoctoral Scholar in the Center for the Physics of Information at Caltech for a year, and then from 2006-2009 he was an Alexander von Humboldt Postdoctoral Research Fellow at the Max Planck Institute of Quantum Optics in Garching, Germany. In 2009, he joined the University of Nebraska – Lincoln as an Assistant Professor.


October 3rd, 2019
3:30PM
110 Physical Sciences

Jason Barnes
Department of Physics
University of Idaho

Dragonfly:  NASA's Rotorcraft Lander mission to Saturn's Moon Titan

Abstract: NASA recently selected the Dragonfly quadcopter, on which I serve as Deputy Principal Investigator, as the fourth mission in its New Frontiers program of planetary missions. Dragonfly will land on the surface of Saturn's hazy moon Titan to explore prebiotic chemistry, to evaluate its habitability, and look for chemical biosignatures.  Titan is one of just 4 planetary bodies that has both a thick atmosphere and a solid surface -- Venus, Earth, and Mars are the others.  Among these, only Titan and Earth have active hydrological cycles with clouds, rain, and surface lakes and seas, though Titan's contain methane and ethane instead of water.  I will discuss the present state of our knowledge about Titan's geology, chemistry, and meteorology, as well as discussion the Dragonfly mission and how it will answer outstanding questions.  (1) How far has prebiotic chemistry progressed toward life?  (2) What potentially habitable biomes might Titan possess, both with respect to water-based life and methane/ethane-based "life, but not as we know it"?  And (3) is there chemical evidence for past or extant life on Titan?

Bio:  Barnes studies the physics of planets and planetary systems. He uses NASA spacecraft data to study planets that orbit stars other than the Sun and the composition and nature of the surface of Saturn's moon Titan. He is deputy principal investigator on the Dragonfly mission proposal to NASA, which would send a robotic rotorcraft lander to explore Titan.  He received his BS degree from Caltech in Astronomy in 1998, and his PhD from the University of Arizona in Planetary Science in 2004.  He has been a Professor of Physics at the University of Idaho since 2008.

 

 


 

August 22, 2019
1:30PM
155 Physical Sciences II, HEP Meeting Room

Electroweak baryogenesis, experimental status, progress and extensions

Dr. Graham White, TRIUMF

 

 


August 20, 2019
1:00PM
147 Physical Sciences II

Prof. Pavel Avramov
Kyungpook National University
Republic of Korea

Downfall from heaven: Unique carbon nanomaterials from superbolide impacts from North-East Russia

Abstract: Unique physical properties and atomic structure of real impact diamonds from Popigai astrobleme (Yakutia, North-East Russia) and exotic closed-shell multiply twinned graphite microcrystals found in Chelyabinsk superbolide dust (Feb 15, 2013, Ural mountains, Northern Russia) were studied using ab initio DFT and MD simulations. The key features of unique atomic structure and mechanical properties of the carbon nano- and microcrystals extracted from real impact and meteorite materials were interpreted using electronic structure calculations. The unique scale and dramatic consequences of both historic events for dinosaur existence and human history makes a theoretical consideration of the carbon nanostructures critically important for survival of entire humanity.


July 18, 2019
3:30PM
110 Physical Sciences

The Ionizing Radiation Environment for Human Space Flight: Risks and Mitigations

Dr. Ramona Gaza, NASA/HH&P Radiation SME and MARE Science Lead, Leidos, Houston, Texas
Dr. Razvan Gaza, Orion Radiation SME and MARE Project Manager, Lockheed Martin Space, Bethesda, Maryland

Space is a harsh environment for human explorers. Ionizing radiation occurs naturally in space, and can have detrimental effects on both the spacecraft hardware and the health of the astronaut crew.

This presentation provides an overview of the space ionizing radiation environment, NASA radiation measurements and instrumentation, models and tools used for radiation exposure predictions, space weather forecasting needs for long duration exploration missions, and exposure risks and mitigation with a focus on crew health. The particularities are discussed of the environmental components and the implications on risk assessments and spacecraft shielding efficiency.

NASA’s Exploration Program aims to return astronauts to the Moon by 2024. The Orion spacecraft is the first Exploration architecture element, and the first NASA human spacecraft to include design requirements for crew radiation protection. Orion is designed by Lockheed Martin as prime contractor. Its maiden flight Exploration Flight Test 1 (EFT-1) was successfully completed in 2014. The trajectory exposed the spacecraft to the core of the Van Allen proton belts. This provided an opportunity for validating the radiation shielding predictions by measurements. The results indicated good correlation with pre-flight predictions. Orion’s next test flight Artemis 1, formerly known as Exploration Mission 1 (EM-1) is scheduled for 2020. The 21-42 day mission to cis-lunar space provided the opportunity for a large scale international radiation experiment referred to as the Matroshka AstroRad Radiation Experiment (MARE). MARE consists of two radiotherapy phantoms—named Zohar and Helga—located in the Orion seats #3 and #4, and fitted with an extensive complement of passive and active radiation detectors. Zohar is also fitted with AstroRad—a novel individual astronaut radiation shield manufactured by StemRad Israel. This allows simultaneous characterization of the intravehicular radiation environment and mitigation efficiency. NASA, the German Aerospace Center DLR, and the Israeli Space Agency ISA are the co-principal investigators to MARE. The co-investigator team consists of dosimeter providers from 10 countries on 3 continents, and includes the Department of Physics at OSU. Lockheed Martin facilitates MARE by as payload integrator and liaison to the Orion Program on behalf of the international science team.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.