SPRING 2024
PHYSICS Colloquium
February 29, 2024
3:30pm CST
110 Physical Sciences
Reception: PS 147, 3:00pm
Dr. Zhenjie Yan
Postdoctoral Fellow
Department of Physics
University of California, Berkeley
Title: Cavity-enabled measurements and interactions in neutral atoms
Abstract: Control over interactions and measurements in quantum systems is crucial for applications such as quantum simulation and computation. In this talk, I will highlight our recent progress in realizing nondestructive readout and long-range interactions in atomic tweezer arrays using a strongly coupled optical cavity. Through selectively coupling a single atom with the cavity mode, we achieve a rapid mid-circuit measurement without perturbing the quantum coherence of the other atoms. Conversely, the collective emission from multiple atoms into the cavity can be coherently enhanced or suppressed. By controlling the atom-cavity interaction at the single-atom level, we observe both super- and subradiant cavity emissions from the constructed atomic ensembles. I will then discuss how we engineer long-range mechanical interactions via photon exchange and present our recent observation of a self-organization phase transition in a mesoscopic system. Finally, I will discuss how the cavity can be used to monitor and manipulate strongly interacting quantum gases, opening new avenues for experimental research in quantum many-body physics.
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PHYSICS Colloquium
February 27, 2024
3:30pm CST
110 Physical Sciences
Reception: PS 147, 3:00pm
Dr. Coraline Fujiwara
Postdoctoral Fellow
Department of Physics
University of Toronto, Canada
Title: Quantum simulation with excited bands of the Bose and Fermi Hubbard Model
Abstract: Over the past few decades, ultracold atomic gases have emerged as an exciting playground for the curious minded to probe many-body quantum physics in a technique known as quantum simulation. Here, the motion of neutral atoms in crystalline-like optical potentials enable experimentalists to realize the Hubbard model, which predicts a wide variety of condensed matter phenomena. A particularly enticing avenue of exploration is to go beyond the ground band and incorporate excited states of the lattice potential. This extension greatly enhances the range of phenomena that we can study in the laboratory. In this talk, I shall first introduce the fundamental concepts of ultracold atoms and quantum simulation in optical lattices. Then I will discuss a few illustrative experiments probing transport and interaction phenomena and how they are enriched by considering excited bands. This will conclude with a discussion of how we can apply such systems to investigate non-equilibrium quantum physics and quantum thermalization. In parallel, I will highlight the important role of students in the research laboratory and my vision for next-generation cold atom experiments.
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PHYSICS Colloquium
February 22, 2024
3:30pm CST
110 Physical Sciences
Reception: PS 147, 3:00pm
Dr. Debayan Mitra
Associate Research Scientist
Department of Physics
Columbia University
Title: Cooling the hydrogen atom without actually cooling it
Abstract: Recent progress in laser cooling atoms and molecules have brought increasingly complex systems into the ultracold regime. This has enabled new opportunities in studying quantum many-body phenomena and exploring the limits of fundamental physics. The hydrogen atom still remains the holy grail of AMO physics because of its simplicity. It is the smallest atom composed of only one proton and electron and this allows for theoretical calculations with unprecedented precision. However, laser cooling the hydrogen atom has eluded physicists for decades due to its light mass and the large recoil of the photon. In this talk, I will describe how we are attempting to circumvent the difficulty of cooling the atom by cooling instead the diatomic hydride molecule - CaH and its fermionic isotopologue CaD. I will summarize the exciting recent developments in the field of AMO physics that have made it possible to cool CaH and show how we plan on achieving the goal of an ultracold and trapped gas of hydrogen atoms.
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PHYSICS Colloquium
February 15, 2024
3:30pm CST
110 Physical Sciences
Reception: PS 147, 3:00pm
Dr. Lee Liu
Postdoctoral Research Associate
Department of Physics
University of Colorado, Boulder
Title: Quantum state-resolved spectroscopy of C60: Exploring symmetry, complexity, and emergence
Abstract: Single polyatomic molecules can exhibit striking emergent phenomena due to their symmetry, complexity, and rich spectrum of collective excitations. I will show how quantum state-resolved spectroscopy in an ensemble of gas phase molecules allows us to probe these dynamics in the *molecular frame*. This circumvents the difficulties of trapping and orienting a complex and symmetric molecule in the *lab frame*.
We experimentally explore these ideas in a familiar molecule: C60. Its rigidity and symmetry make it the largest molecule for which quantum state resolution has been achieved, marking a new frontier in many-body physics. We resolved the rotational fine structure of C60 for the first time, revealing surprising emergent behaviour mediated by symmetry and molecular rotations. I will conclude with prospects for using spectroscopy of C60 and other complex molecules to explore new emergent phenomena.
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PHYSICS Colloquium
February 1st, 2024, Thursday, 3:30pm CST
Where: 110 Physical Sciences
Reception: PS 147, 3:00pm
Dr. Patricia H Reiff
Professor, Physics and Astronomy
Associate Director for Outreach Programs
Rice Space Institute
Title: The Sun, Reconnection, and The Eclipse
Abstract: Solar eclipses are a rare opportunity to see a plasma in action. The coronal light is made up of scattered light from the photosphere (which is polarized) and emission lines from ionized heavy elements in the corona. We can use the amount of ionization to determine the coronal temperature, and the polarization to monitor the connectivity of the magnetic fields. The corona is heated far above the photospheric temperature (6000C) by small-scale magnetic reconnection fueled by stirring of the solar surface. The Magnetospheric Multiscale mission (MMS) has for the first time uncovered the source of the parallel electric fields which contribute to the bulk of the plasma heating during reconnection. The Citizen CATE project will place 35 identical solar telescopes along the center line from Del Rio to Maine, to take images of the corona in polarized light. By combining the images taken by the telescope array, we can uncover reconnection happening near the surface of the Sun. Totality April 8, 2024, passes through northeast Texas, southeast Oklahoma and Arkansas, so plan to get inside the zone of totality if you at all can - this spectacle won’t return to Oklahoma until 2045. Only in the zone of totality and only DURING totality is it safe to remove your solar filters and see the amazing corona at solar max!
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FALL 2023
Quantum Information Science Journal Club
October 25, 2023, Wednesday, 4:30pm CST
Where: 147 Physical Sciences
Jared Austin-Harris
Department of Physics
College of Arts and Science
Oklahoma State University
Quantum Critical Dynamics and Indirect Microscopy of a Spinor Hubbard Model Quantum Simulator
ABSTRACT: Quantum simulators are easily controllable quantum systems that allow us to physically model the behavior of more complex systems, that are intractable with even the most advanced supercomputers, to gain insight into their behavior. Here, I describe my work using lattice confined spinor Bose-Einstein condensates (BEC) as quantum simulators to probe, among other things, the superfluid-Mott insulator phase transition. In a quantum version of the Kibble-Zurek mechanism, the spin degree of freedom reveals that the dynamics of a BEC can be frozen by a sufficiently quick ramp across the phase transition. We additionally utilize the discrete energy signatures in the nonequilibrium spin mixing dynamics generated by the atoms that are tightly confined to single lattice sites after a quench across the superfluid-Mott insulator phase transition to understand the spatial dynamics of a BEC during this transition.
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PHYSICS Colloquium
October 24, 2023, Tuesday, 3:30pm CST
Where: 103 Physical Sciences
Reception: PS 147, 3:00pm
Dr. Mario Borunda
Associate Dean and Associate Professor
Department of Physics
College of Arts and Science
Oklahoma State University
Radiation Resilience: Unveiling the Secrets of Halide Perovskites
ABSTRACT: Many of the challenges experienced by halide perovskite materials, such as degradation caused by exposure to oxygen or water, limit their usage in ordinary environments. However, this solar cell must survive radiation exposure to operate in space. I will present our ab initio molecular dynamics (AIMD) simulations for different halide perovskites to investigate their response to low-energy radiation. The simulations help estimate non-ionizing radiation damage in materials, the primary degrader of optoelectronic properties under radiation environments. These efforts would allow for a better understanding of the radiation hardness of materials.
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PHYSICS Colloquium
October 19, 2023, Thursday, 3:30pm CST
Where: 103 Physical Sciences
Reception: PS 147, 3:00pm
Dr. Srubabati Goswami
Physical Research Laboratory, India
& Northwestern University
FROM AN IMPOSSIBLE DREAM TO THE UNREACHABLE STARS: THE JOURNEY OF THE NEUTRINO
ASTRACT: Neutrinos were proposed by Wolfgang Pauli to explain the principle of conservation of energy in nuclear beta decay. This weakly interacting and electrically neutral particle was detected, almost three decades after it was postulated, by Clyde Cowan and Frederick Reines. Since then neutrino physics has remained an active and interesting area of research, Neutrinos also carry information from distant stars. This talk will trace the journey of the neutrino from the impossible dream of Pauli to the observation of neutrinos from unreachable stars, by the state of the art ICECUBE detector at the south pole. It will also discuss some unique properties of neutrinos which compel us to think beyond the standard ideas and open a new window towards a deeper understanding of nature.
High Energy Seminar
October 17, 2023, Thursday, 12:00pm CST
Where: 147 Physical Sciences
Dr. Srubabati Goswami
Physical Research Laboratory, India
& Northwestern University
The Fable of the Unstable Neutrinos
Neutrino decay is governed by a non-Hermitian effective Hamiltonian and in general the mass eigenstates and decay eigenstates are not the same. This mismatch is inevitable in the presence of matter and the Hermitian and anti-Hermitian components cannot be simultaneously diagonalized by unitary transformations for all matter densities. In this talk a formalism for treating the two-flavor neutrino propagation through matter of uniform density, for neutrino decay to invisible states, will be discussed. First, it will be shown how employing a resummation of the inverse Baker-Campbell-Hausdorff or Zassenhaus expansion, compact analytic expressions for neutrino survival and conversion probabilities can be obtained. We will also discuss the approximate analytic probabilities in the three generation framework and show the baselines and energies where the different approximations give good matching with the numerical probabilities. These results provide physical insights into the effects of neutrino decay at long-baseline neutrino oscillation experiments.
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PHYSICS Colloquium
October 12, 2023, Thursday, 3:30pm CST
Where: 103 Physical Sciences
Reception: PS 147, 3:00pm
Dr. Konstantin Matchev
University of Florida
Machine learning symmetries in physics from first principles
Abstract: Symmetries are the cornerstones of modern theoretical physics, as they imply fundamental conservation laws. The recent boom in AI algorithms and their successful application to high-dimensional large datasets from all aspects of life motivates us to approach the problem of discovery and identification of symmetries in physics as a machine-learning task. In a series of papers, we have developed and tested a deep-learning algorithm for the discovery and identification of a continuous group of symmetries present in a labeled dataset. The method will be illustrated with several practical examples of increasing mathematical complexity.
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SPRING 2023
PHYSICS Colloquium
March 23, 2023, Thursday, 3:30pm CST
Where: 110 Physical Sciences
Reception: PS 147, 3:00pm
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DR. MARK DEAN
Condensed Matter Physics and Materials Science Department
Brookhaven National Lab
X-RAY VISION OF ELECTRON BEHAVIOR IN QUANTUM MATERIALS
ABSTRACT: Many of the most remarkable properties of quantum materials come from the interplay of multiple charge, orbital, and spin degrees of freedom. Probing all of these with a single technique is consequently highly desirable. In this talk, I will describe the experimental technique of resonant inelastic x-ray scattering (RIXS) and its unique capabilities to probe all these degrees of freedom even in atomically thin samples or at ultrafast timescales. This will be illustrated by some of our work on iridium-based magnetic materials including the discovery of a novel “antiferromagnetic excitonic insulator” [1] and efforts to control magnetism via ultrafast laser excitation [2-3]. I will finish by outlining future research opportunities in this area.
[1] Antiferromagnetic excitonic insulator state in Sr3Ir2O7, D. G. Mazzone et al., Nature Communications 13, 913 (2022)
[2] Laser-induced transient magnons in Sr3Ir2O7 throughout the Brillouin zone
D. G. Mazzone, et al., Proceedings of the National Academy of Sciences 118, e2103696118 (2021)
[3] Ultrafast energy and momentum resolved dynamics of magnetic correlations in photo-doped Mott insulator Sr2IrO4, M. P. M. Dean et al., Nature Materials 15, 601–605 (2016)
PHYSICS Colloquium
February 28, 2023, Tuesday, 3:30pm CST
Where: 110 Physical Sciences
Reception: PS 147, 3:00pm
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DR. JULIUS DE ROJAS
Postdoctoral Research Associate
Durham University
Current(less) Trends in Spintronics: Magnetoionics & Magnonics for Energy Efficient Computing
ABSTRACT: The invention of the transistor 75 years ago kicked off a revolution in computing, and with it immense technological and societal progress. However, quickly approaching fundamental hurdles, including power constraints and manufacturing limitations, have left conventional computing hardware struggling to maintain energy efficiency as dimensions continue to shrink. To meet these challenges, hardware must move towards energy efficient approaches to data storage and processing. In this talk, I will overview the challenges facing conventional computing structures and discuss how emerging spintronic approaches such as magneto-ionics and magnonics provide a potential path forward. I will overview our work in magneto-ionics, an emerging subfield of spintronics in which material properties can be tuned by moving ions into and out of magnetic material under low-power, and I will discuss novel functionalities in oxygen-based and nitrogen-based systems. I will then conclude with my recent research in magnonics, in which spin-waves are used transport and process data and discuss our work on extending artificial spin ice systems to pseudo-3D structures.
PHYSICS Colloquium
February 23, 2023, Thursday, 3:30pm CST
Where: 110 Physical Sciences
Reception: PS 147, 3:00pm
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DR. JINSONG XU
Postdoctoral Fellow
Johns Hopkins University
DISCOVERY OF NEW SPIN CURRENT PHENOMENA IN QUANTUM MATERIALS
ABSTRACT: Spin, the basis of spintronic devices in information technology, provides new and effective ways to probe and control the state of quantum materials. A pure spin current has the advantage of delivering spin angular momentum with reduced energy dissipation and holding promise for the next generation devices. In this talk, I describe spin current phenomena and our discoveries in the following two areas: Vector spin Seebeck effect (SSE) and spin swapping effect in noncollinear antiferromagnets (AFs): With negligible stray field and high frequency dynamics, AFs hold promise for high-speed and high-density storage devices. Most studies to date have been conducted in collinear AF systems, which severely restrict the spintronic phenomena. I will describe our recent studies on noncollinear AF insulators LuFeO3 and LaFeO3 [1,2], and the discovery of vector SSE including both longitudinal and transverse SSE, where the latter is absent in collinear systems and never observed before. We identified spin swapping effect as the mechanism for transverse SSE, likely from the noncollinear spin structures. These noncollinear AF insulators expand new realms for exploring spin current phenomena and provide a new route to low-field AF spintronics and magnonics. Seebeck-contrast measurements for magnon Hall effect (MHE): MHE in topological magnon insulators with strong Berry curvature effects, the analogue of the well-known anomalous Hall effect (AHE) in ferromagnetic metals, was first discovered in Lu2V2O7 in 2010. To date, MHE could only be detected by the challenging thermal Hall conductivity measurements. We have recently demonstrated a new and simpler method of electrical detection of MHE [3]. Moreover, we established a protocol of Seebeck-contrast measurement to differentiate among MHE, SSE and anomalous Nernst effect (ANE), and found that there is spin current associated with MHE. The electrical method for MHE paved ways for exploring new topological magnon insulators and their applications for spintronics.
PHYSICS Colloquium
February 16, 2023, Thursday, 3:30pm CST
Where: 110 Physical Sciences
Reception: 3:00pm in PS 147
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DR. VEDRAN BRDAR
Senior Research Fellow
CERN
NEUTRINOS AT PRESENT AND NEAR FUTURE EXPERIMENTS: STANDARD MODEL AND BEYOND
ABSTRACT: Despite having already been awarded a Nobel Prize, the golden age of neutrino oscillation experiments is only just beginning. In addition to solving the remaining puzzles in the standard three-neutrino framework, neutrino experiments are also sensitive to new physics effects that could appear in the process of neutrino production, propagation and/or detection. In the first part of this talk, I will introduce a novel manifestation of physics beyond the Standard Model, testable already at present-day accelerator based experiments such as NOvA and T2K, which is based on the fact that neutrino mixing parameters at the scale of neutrino production and detection do not necessarily need to coincide. This will be shown in the context of a particular neutrino mass model within which large renormalization group effects occur. In the second part of the talk, I will address the anomalous findings of the MiniBooNE experiment, which have been touted as either a possible hint for new physics, or a reflection of our poor understanding of neutrino-nucleus interactions. I will address this anomaly by critically examining a number of theoretical uncertainties affecting the event rate prediction at MiniBooNE, focusing on charged current quasielastic events, single-photon events, and those from neutral pion decay. This will allow me to discuss the dependence of the statistical significance of the anomaly on such uncertainties. I will also critically examine new physics explanations of MiniBooNE anomaly, focusing on eV-scale sterile neutrinos. In the last part of the talk, I will discuss the potential of DUNE, the leading US-based neutrino experiment for the next decade, for probing light dark sectors, and will take axion-like particles (ALPs) as an example. At DUNE, the high-intensity proton beam impinging on a target will not only produce neutrinos, but will also yield copious amounts of photons, allowing for photophilic ALPs to be produced with high intensity. I will show that a wide range of ALP parameter space, including regions unconstrained by existing bounds, will be explored at DUNE.
PHYSICS Colloquium
February 14, 2023, Tuesday, 3:30pm CST
Where: 110 Physical Sciences
Reception: 3:00pm in PS 147
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DR. DOOJIN KIM
Physics & Astronomy
Texas A&M University
MAGIC CARPET RIDE TO A NEW PHYSICS WORLD
ABSTRACT: While the Standard Model is a successful description for mutual interactions and relationships of elementary particles, there are still issues and phenomena such as dark matter and non-zero mass of neutrinos that are unexplained by the Standard Model, hence motivating new physics beyond the Standard Model. Many theoretical considerations and experimental efforts thus far suggest that many of the related new particles are very weakly or feebly interacting with known particles and they may be sitting in "blind" spots that existing and near-future experiments across colliders, neutrino facilities, and cosmic-frontier experiments can be sensitive to. A possible way of exploring new physics scenarios in these experiments is to revisit familiar physics ideas and take a closer look at their overlooked physical implications. In this context, we will discuss three examples, energy peak, charged mesons, and superlight dark matter. For the energy peak, we will argue that energy, a Lorentz-variant quantity, has a subtle but hidden invariance property and discuss how it can be used in high energy physics experiments, especially at colliders. For the charged mesons, we will show that charged mesons can be great but overlooked sources of new physics particles and discuss their physics applications in various experiments including the beam-focused neutrino experiments and the complementarity among them. Finally, we will briefly discuss a new idea to detect superlight dark matter using a graphene Josephson Junction-based bolometer device that is sensitive to the sub-meV scale energy deposit, and related physics opportunities.
PHYSICS Colloquium
February 9, 2023, Thursday, 3:30pm CST
Where: 110 Physical Sciences
Reception: 3:00pm in PS 147
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DR. GILLY ELOR
Mainz Institute for Theoretical Physics
Johannes Gutenberg University
MESOGENESIS
ABSTRACT: What is the Universe made of? Why do complex structures such as ourselves exist? I will present a proposal for simultaneously solving both these outstanding mysteries of particle physics: Mesogenesis, which generates both the observed asymmetry of matter over antimatter in the early Universe, and the population of Dark Matter particles. Mechanisms of Mesogenesis generate an asymmetry through strongly coupled Standard Model particles known as mesons. Excitingly, this makes Mesogenesis highly testable and it can be searched for at the Large Hadron Collider, electron positron colliders, and even large volume neutrino experiments. Many experimental searches are currently underway to test Mesogenesis and I will present an overview of these exciting ongoing efforts.
PHYSICS Colloquium
February 7, 2023, Tuesday, 3:30pm CST
Where: 110 Physical Sciences
Reception: PS 147, 3:00pm
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DR. RAYMOND CO
University of Minnesota
AXION DYNAMICS PUTS A NEW SPIN ON SOLVING COSMOLOGICAL MYSTERIES
ABSTRACT: The QCD axion is a hypothetical particle proposed to solve the strong CP problem and thus explain why neutrons have a vanishing electric dipole moment. The axion has long been known to be an excellent candidate for dark matter, which must exist to explain the motion of stars and galaxies. We have discovered novel axion dynamics in the early universe, called axion rotations, which may naturally occur as a result of quantum gravity effects and cosmic inflation. This dynamic was overlooked in the extensive literature but has profound consequences. In this talk, I will discuss the example where axion rotations can simultaneously generate axion dark matter and the observed excess of matter over antimatter in the Universe. Remarkable, rich phenomenology automatically arises with sharp, distinct, and correlated predictions. These include specific axion properties, unique gravitational wave signals, and correlated mass scales of supersymmetry and neutrinos. Models with decaying heavy axions may be tested by neutrino experiments such as DUNE and long-lived particle searches at the LHC. Thus far, axion rotations have added fuel to experimental efforts and paved new theory research avenues, opening up resolutions to the deepest cosmological mysteries with discoverable signatures.
PHYSICS Colloquium
January 26, 2023, Thursday, 3:30pm CST
Where: 110 Physical Sciences
Reception: PS 147, 3:00pm
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DR. NICKOLAS SOLOMEY
Wichita State University
A POSSIBLE NEUTRINO AND DARK MATTER
EXPERIMENT IN SPACE
ABSTRACT: We are building a test detector capable of operating in space with the possibility to do improved studies of solar neutrinos and dark mater searches in space. This detector prototype is supported by NASA to fly a 3U CubeSat with a possible launch date of Summer 2024. If a detector capable of operating in space is sensitive to neutrinos that can be distinguished from the many different backgrounds in space, then it would allow a series of experiments in space such as going closer to the Sun where the neutrino flux increases 1,000x to 10,000x above that of earth, or going away from the Sun to search for Dark Matter where the solar neutrino background is five order of magnitude less. This technique is a double delayed coincidence from the conversion electron and excited start nuclear gamma decays with 2.5 microseconds. The aim of our CubeSat test flight is to test the detector concept idea in space operations and study real deep space backgrounds that can emulate the double delated coincidence signal.
FALL 2022
SPRING 2022
PHYSICS Colloquium
April 21 2022, Thursday, 3:30 pm CST
Physical Sciences 110
Dr. 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
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
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
Dr. 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
Dr. 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
Dr. 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
Dr. 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
Dr. 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
Dr. 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
Dr. 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
Dr. 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 ColloquiumSeptember 16 2021, Thursday, 3:30 pm CSTPhysical Sciences 110Dr. Erin Iski
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PHYSICS ColloquiumSeptember 23 2021, Thursday, 3:30 pm CSTPhysical Sciences 110Dr. Francesco (Frank) NarducciNaval Postgraduate SchoolAssociate Editor: Physical Review A, Physical Review Letters
Towards a T3 atom interferometerIn 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.
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PHYSICS ColloquiumSeptember 30 2021, Thursday, 3:30 pm CSTPhysical Sciences 110Dr. David TománekMichigan State UniversitySaving Humankind from ThirstWhereas 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 ColloquiumOctober 28 2021, Thursday, 3:30 pm CSTVia Zoom (contact Physics Department for link)
Dr. Phillip RyanArgonne National LaboratoryX-ray scattering and Electrical Measurements of Uniaxially Strained Single Crystals: Unconventional Superconductors and Single Phase MultiferroicityIn 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).
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PHYSICS ColloquiumNovember 4 2021, Thursday, 3:30 pm CSTPhysical Sciences 110Dr. 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.
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SPRING 2021
Physics department colloquia in 2021 via Zoom
PHYSICS ColloquiumMay 5 2021, Thursday, 11:00 am CST (Followed by Q&A with speaker: 11:45-12:15)Via Zoom (contact Physics Dept. for link) Dr. Andreas VasdekisUniversity of IdahoStochastic Cellular Dynamics, Human Health Implications, and Related MethodsNo 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.
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PHYSICS ColloquiumBeing rescheduled for Fall Semester (in-person!)Dr. Erin Iski
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PHYSICS ColloquiumApril 7 2021, Wednesday, 4:00 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Seth DarlingUniversity of Chicago and Argonne National LaboratoryWater technologies by interface engineeringDriven 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 ColloquiumMarch 31 2021, Wednesday, 3:30 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Midhat FarooqAPS Career Program Manager
Physics Careers: the Myths, the Data, and Tips for SuccessPhysics 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.
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PHYSICS ColloquiumMarch 24 2021, Wednesday, 3:30 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Paul KwiatUniversity of Illinois Urbana-Champaign
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PHYSICS ColloquiumMarch 18 2021, Thursday, 3:30 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Gabriela B. LemosInstituto de Fisica
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PHYSICS ColloquiumMarch 11 2021, Thursday, 3:30 pm CSTVia Zoom (contact Physics Dept. for link) Dr. John EllisKing's College London & CERNGrand Unified Theories and Proton DecayGiven 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!
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PHYSICS ColloquiumMarch 3 2021, Wednesday, 3:30 pm CST
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PHYSICS ColloquiumFebruary 25 2021, Thursday, 3:30 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Ajit SrivastavaInstitue of Physics, Bhubaneswar
Investigating Cosmic string theories with Liquid Crystal ExperimentsSpontaneous 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 ColloquiumFebruary 18 2021, Thursday, 1:00 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Joe SmerdonUniversity of Central Lancashire
Adsorption of fullerene and pentacene on Cu(111)
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PHYSICS ColloquiumFebruary 11 2021, Thursday, 4:00 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Yue CaoArgonne National Lab
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 ColloquiumFebruary 4 2021, Thursday, 4:00 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Harry E. RudaUniversity of Toronto
A superficial tale: How semiconductor nanowires offer a remarkable platform for nanoelectronics and sensingThe 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 ColloquiumJanuary 28 2021, Thursday, 4:00 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Sunil ChirayathCenter for Nuclear Security Science and Policy Initiatives, Texas A&M University
Role of Nuclear Security Education in the Peaceful Uses of Nuclear EnergyElectricity 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 ColloquiumJanuary 21 2021, Thursday, 4:00 pm CSTVia Zoom (contact Physics Dept. for link) Dr. Adina Luican-Mayer
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HEP SeminarJanuary 21 2021, Thursday, 12:00 pm CST
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OKPVRI Annual Meeting & SymposiumJanuary 15 2021
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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
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
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
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, 2020
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
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.