Current Seminars and Colloquia

Article Index

SPRING 2024

PHYSICS Colloquium
February 29, 2024

3:30pm CST

110 Physical Sciences

Reception: PS 147, 3:00pm

Zhenjie Yan300

 

 

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

cora fujiwara head shot.max 200x200

 

 

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

DM img 300

 

 

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

lee liu 300

 

 

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

 

mario borunda web square

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

Goswami

 

Dr. Srubabati Goswami

Physical Research Laboratory, India
& Northwestern University

  

FROM AN IMPOSSIBLE DREAM TO THE UNREACHABLE STARS: THE JOURNEY OF THE NEUTRINO

ASTRACTNeutrinos 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

Konstantin Matchev

 

 

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

 

Dean

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

de Rojas

 

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

Jinsong Xu 7 1

 

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

vedran headshot 300

 


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

Doojin Kim 300

 


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

Gilly Elor Headshot 300

 


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

Raymond Co 300

 


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

 

solomey



 

DR. NICKOLAS SOLOMEY
Wichita State University

 

 
A POSSIBLE NEUTRINO AND DARK MATTER
EXPERIMENT IN SPACE

ABSTRACTWe 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.