Department of Physics & Astronomy "Colloquia and Seminars" Series

Virtual or R-150, Hilbun Hall, Mississippi State University

Fridays @ 3:00 PM

Nov. 29^th, 2024 ***** Happy & Safe Thanksgiving Break as well as Holidays Season *****

***** End of the Fall 2024 semester; Hearfelt wishes for Healthy and Properous New Year, 2025 :)! *****

Nov. 22^nd, 2024 Dr. Timilehin Ogunbeku, Physics Division, Lawrence Livermore National Laboratory

   Leveraging the FDSi’s Complete Decay Spectroscopy Capabilities: the Structure of Neutron-rich ⁵⁴Sc

  Host: Dr. Ben Crider

  Instruction: In-person in Hilbun R-150

  Abstract:

       Advancing our understanding of shell evolution as nuclei become more neutron-rich is essential for improving the predictive power of nuclear models - a key focus of radioactive ion beam facilities like the Facility for Rare Isotope Beams (FRIB). In one of the first experiments at FRIB, a cocktail of neutron-rich nuclei near ⁵⁴Ca was delivered to the two distinct high-resolution and total-absorption focal planes of the FRIB Decay Station initiator (FDSi), enabling comprehensive decay spectroscopy of these exotic nuclei. I will present an overview of the unique capabilities of the FDSi and discuss new results relevant to further understanding the structure of neutron-rich 54Sc which is uniquely positioned just above the Z= 20 shell closure, and between the N= 32 and N= 34 subshell closures.

Nov. 15^th, 2024 Dr. Matthew Knight, Physics Department, U.S. Naval Academy

   The surprising value of comet morphology: using an ancient technique to learn about our solar system’s fossils

  Host: Dr. Donna Pierce

  Instruction: Virtual in ZOOM ONLY

  Abstract:

       Comets are compelling objects of study since they preserve information about the conditions present during our solar system’s formation. These “dirty snowballs” have remained frozen at large distances from the Sun, but become active via the sublimation of their ices when they pass through the inner solar system. This activity releases both dust and gas, obscuring the still frozen nucleus and preventing its direct study. A handful of space missions to comets have yielded great insight into the nature of individual nuclei, but such missions are too costly to investigate the population as a whole. Instead, we rely on remote observations using Earth-based telescopes.
       I will discuss how the study of comets’ morphology, particularly using specialized narrowband filters able to isolate specific gases, allows us to learn about their hidden nuclei. Although assessment of comet morphology has been occurring for centuries, recent advancements have resulted in huge leaps in what information can be gleaned from these observations. Furthermore, we are entering an exciting new era in which JWST and the Rubin Observatory will revolutionize our understanding of comets and related bodies; I will discuss how I am enabling more widespread use of narrowband imaging to complement these next generation facilities.

Nov. 8^th, 2024 Dr. Mahmoud M. Asmar, Physics Department, Kennesaw State University

   Vortex States and Magnetic Interactions in Light-driven Quantum Material

  Host: Dr. Dipangkar Dutta

  Instruction: In-person in Hilbun R-150

  Abstract:

       The discovery of Dirac and topological materials has opened new avenues for electronic and optoelectronic applications. Enabled by advancements in high-intensity, broadband radiation sources, Floquet engineering—a technique that drives systems beyond equilibrium through optical modulation—has gained momentum. This presentation will examine periodically driven two-dimensional Dirac materials, highlighting Floquet engineering’s impact on phenomena such as carrier-mediated magnetic (RKKY) interactions, light-induced topological and vortex states, and the emergence of higher-order topological insulators.

Nov. 1^st, 2024 Mr. Nathan Rutherford, Physics & Astronomy Department, University of New Hampshire

  Probing asymmetric dark matter admixed neutron stars with Bayesian inference and neutron star mass-radius measurements

  Host: Dr. Angelle Tanner

  Instruction: Virtual in ZOOM ONLY

  Abstract:

       Asymmetric dark matter (ADM) can accumulate in neutron star interiors and affect their global properties, such as their masses and radii. Considering the effects of ADM accumulation, neutron stars and their mass-radius measurements can not only be used to deliver new insights into the cold dense matter equation of state (EoS), but also be used as a hunting round for dark matter. In this talk, I will share how we employ Bayesian parameter estimation using current and future neutron star mass-radius data to infer constraints on the combined baryonic matter and ADM EoS, where the ADM is modeled as either a boson or fermion and forms a core in the neutron star interior. For the remainder of the talk, I will discuss the results that we have inferred from this Bayesian approach.

Oct. 25^th, 2024 Dr. Shao-kai Jian, Physics & Engineering Department, Tulane University

   Novel physics at the temporal boundary

  Host: Dr. Dipangkar Dutta

  Instruction: In-person in Hilbun R-150

  Abstract:

       Boundary physics plays a crucial role in various disciplines. I will talk about the physics of temporal boundaries created by weak measurements. Firstly, I discuss the effect of measurement and postselection on a Luttinger liquid theory. Depending on the Luttinger parameter K, measurement effects can be irrelevant, marginal, or relevant. When measurement is marginal, a critical state emerges with entanglement entropy exhibiting logarithmic behavior, characterized by a continuous effective central charge. Inspired by these findings, the second part delves into a holographic description of weak measurements. Here, we propose that weak measurement can be modeled by an interface brane, separating different geometries corresponding to the post-measurement and unmeasured states. The effect yields a diverse phase diagram of geometries.

Oct. 18^th, 2024 Dr. Heidrun Schmitzer, Physics & Engineering Department, Xavier University

   A Career in Physics

  Host: Dr. Dipangkar Dutta

  Instruction: In-person in Hilbun R-150

  Abstract:

       In this talk, Dr. Heidrun Schmitzer shares her personal journey and experiences in the field of physics. From her early inspirations and educational background to her current research and professional achievements, she will discuss the challenges and opportunities she encountered along the way. The presentation will highlight key moments in her career, including collaborations, discoveries, and her contributions to the broader scientific community. It aims to inspire young scientists and students by emphasizing the importance of curiosity, persistence, and teamwork in shaping a successful career in physics.

Oct. 11^th, 2024 Fall Break: No Colloquium; Enjoy :) and be Safe!

Oct. 4^th, 2024 Dr. Grigory Rogachev, Department of Physics & Astronomy, Texas A&M University

   Clustering in nuclei – the present state-of-the-art

  Host: Dr. Anatoli Afanasjev

  Instruction: In-person in Hilbun R-150

  Abstract:

       Multi-nucleon correlations or nuclear clusters play an important role in nuclei, often determining the level structure and nuclear reactions cross sections. A better understanding of clustering in nuclei is necessary not only from the fundamental nuclear theory perspective but also from the point of view of nuclear astrophysics. The α-particle-induced reactions, such as α-capture, (α,n) and (α,p) are essential in stellar nucleosynthesis and they are often dominated by α-cluster degrees of freedom in participating nuclei. We will review the experimental evidence for clusters in nuclei, discuss the modern experimental techniques applicable to study clustering and benchmark the theoretical predictions.

Sept. 27^th, 2024 Dr. Santanu Banerjee, Physics Department, Tougaloo College

   Revolutionizing our future: Novel Applications of Nanotechnology in Environmental and Biomedical fields

  Host: Dr. Dipangkar Dutta

  Instruction: In-person in Hilbun R-150

  Abstract:

       The size and shape dependent properties of materials, along with the order of magnitudes enhancement of quantum effects at the nanometer scale, provide a new armory of tools to combat pressing environmental and biomedical challenges. Consequently, the development and growth of Nanotechnology has created novel solutions to broad ranging problems in these fields. A subset of such applications, which are highly sensitive and selective, primarily utilizing modified gold nanomaterials, will be discussed in this seminar.
      Arsenic pollution in ground water is a grave threat, estimated to be affecting 150 million people globally. The current lab-based methods of ground water Arsenic detection are time consuming and expensive. As an alternative, we have developed a glutathione (GSH), dithiotreitol (DTT), and cysteine (Cys) modified gold-nanoparticle based colorimetric assay for detection of Arsenic at a detection limit well below the World Health Organization guidelines (10-50 ppb, based on location), and selectivity over other analytes. We have also developed a dynamic light scattering (DLS) based assay, with an excellent detection limit (100 ppt).
      Biological as well as bioterrorism threats through microbes such as Salmonella and E-coli constitutes an urgent need for quick and easy detection and destruction of such agents. Using the corresponding antibody (anti-Salmonella or anti-Ecoli) conjugated gold nanoparticles can readily and specifically identify the respective microbes, utilizing antibody-antigen recognition through observed colorimetric change. This colorimetric change occurs due to aggregation of nanoparticles on the surface of the bacteria, leading to size dependent change in optical properties of the nanomaterials. A similar antibody-antigen interaction can be used for detection of specific cancer cells at very low concentrations. Furthermore, photothermal therapy using infrared lasers (benign non-ionizing radiation) can be utilized for selective destruction of harmful microbes or cancer cells, without affecting normal cells. Applications to anti-microbial resistant (AMR) bacteria will also be discussed.
      In addition to focusing on the Nanotechnology applications, wider ranging physics related opportunities at Tougaloo College will be briefly addressed, including some appropriate for Mississippi State students.

Sept. 20^th, 2024 Dr. Konstantin Dorfman, School of Physics and Electronic Science, East China Normal University

   High precision spectroscopy in frequency, time, and spatial domains: quantum light, high harmonics, and metasurfaces

  Host: Dr. Gombojav Ariunbold

  Instruction: Virtual in ZOOM ONLY

  Abstract:

       In the first part of the talk, we will discuss how new quantum phenomena in complex systems can be studied and controlled using advances in both quantum optics and nonlinear spectroscopy. In particular, I investigate how to probe, control, and image the spectral information of these complex systems using squeezed quantum state of light generated via four-wave mixing and reveal the material information, which is not accessible by conventional classical photonics tools. The biphoton technique allows to extend quantum spectroscopy of time domain by nonlocal wavelength- to time mapping.
       In the second part of the talk, we will discuss a novel method for monitoring electronic coherences using ultrafast spectroscopy. This method is based on the time-domain high-order harmonic spectroscopy where a coherent superpostion of the electronic states is first prepared by the strong optical laser pulse using a three-step mechanism introduced by Lewenstein and Corkum. The coherent dynamics can then be probed by the higher order harmonics generated by the delayed probe pulse. A semi-perturbative model based on the Liouville space superoperator approach is developed for the bookkeeping of the different orders of the nonlinear response for the high-order harmonic generation using multiple pulses. Coherence between bound electronic states is monitored in the harmonic spectra from both the first and the second order responses and investigate nonadiabatic dynamics of conical intersections and avoided crossings. The multidimensional version of the technique allows for selective elimination of inhomogeneous broadening which allows to extend the strong field techniques to large macromolecules and materials.
      In the last part of the talk, we will present the metasurfaces as a novel platform for optical spectroscopy. Relying on the local orientation of nanostructures, Pancharatnam–Berry (PB) metasurfaces are currently enabling a new generation of polarization sensitive optical devices. A systematical mesoscopic description of topological metasurfaces is developed, providing a deeper understanding of the physical mechanisms leading to the polarization-dependent breaking of translational symmetry in contrast with propagation phase effects. Our theoretical model, which allows clear understanding of PB phase is proven in an experimental measurement involving Mach-Zehnder interferometric setup. We further demonstrate that the reconstruction of a multidimensional nonlinear polarization response of a nanomaterial can be achieved in a single heterodyne measurement by active manipulation of the polarization states of incident light. Using multidimensional spectroscopy, we show the possibility to track both stationary and transient delocalized charge distributions via detecting plasmonic populations and coherences.

Sept. 13^th, 2024 Ms. Claire Geneser, Physics & Astronomy Department, Mississippi State University

   Gaussian Process Modeling for Mass Estimates of Exoplanets around Active Stars

  Host: Dr. Lamiaa El Fassi

  Instruction: In-person in Hilbun R-150

  Abstract:

       Exoplanet candidates identified by the Transiting Exoplanet Survey Satellite (TESS) often require 50 or more follow-up observations before determining a mass measurement. This requires the use of specially designed echelle spectrographs from which we are able to retrieve precise radial velocity (PRV) measurements. The number of observations surges when measuring PRVs in the presence of strong stellar variability. This pertains to most observations of planets around adolescent or young K dwarf stars. Our candidate, TOI-2443 b, is a sub-Neptune mass planet with an orbital period of 15.669 days and a radius of 2.69 R_earth in orbit around a relatively adolescent star which exhibits stellar variability of nearly 15 m/s. The PRV time series is modeled with a Gaussian Process (GP) which fits the stellar activity as a function of wavelength for each spectrograph. Combining PRV measurements at visible and near-infrared wavelengths reduces the impact of star spots or other sources of stellar variability on the time series which can be misinterpreted as a planetary signal. In this presentation, we review preliminary results of TOI-2443 b and we demonstrate how the GP model is able to recover a planetary signal through a sea of stellar variability.

Sept. 6^th, 2024 Dr. Gautam Rupak, Physics & Astronomy Department, Mississippi State University

   Nuclear structure, reactions and quantum computers

  Host: Dr. Lamiaa El Fassi

  Instruction: In-person in Hilbun R-150

  Abstract:

       Scattering experiments are fundamental to understanding the microscopic structure of quantum objects. Scattering is a real-time process. However, realistic quantum many-body calculations on classical computers are usually done with Monte Carlo simulations in imaginary times. These calculations also suffer from severe signal to noise ratio problem as the system size grows. An algorithm for the real-time calculation of inelastic processes, on a quantum computer is presented. We demonstrate the feasibility of the method with several proof of principle calculations involving quantum computing hardware.

Aug. 30^th, 2024 Dr. Daniel Tapia Takaki, Physics & Astronomy Department, The University of Kansas

   Photons at the Energy Frontier

  Host: Dr. Lamiaa El Fassi

  Instruction: In-person in Hilbun R-150

  Abstract:

       The study of ultraperipheral nuclear collisions (UPCs) is breaking new grounds in fundamental physics. Although experiments at BNL RHIC and at the CERN LHC are not designed to exploit photon-induced interactions there is a plethora of recent results on UPCs in a wide variety of subjects: imaging the nucleus, studying fundamental electromagnetic and electroweak processes, probing the nuclear matter, and searches for physics beyond the Standard Model. In this talk, we will discuss a selection of recent UPC studies, as well as new directions in light of new theoretical and phenomenological studies, including novel applications of quantum mechanics.

Aug. 23^rd, 2024 Dr. Wenliang (Bill) Li$*$ and Dr. Jaspreet S. Randhawa$**$, Physics & Astronomy Department, Mississippi State University

   $*$ Probing Proton's Identity using the Future EIC

   $**$ Decoding X-ray Binaries using Exotic Beams

  Host: Dr. Lamiaa El Fassi

  Instruction: In-person in Hilbun R-150

  Abstract:

      $*$ Proton as a member of the baryon family, holds a baryon number (identity) of one. Unlike the structureless leptons, the baryons are constructed of quarks and gluons. We will dive into the mystery of who carries the identity (baryon number) for the proton with the help from the future Electron-Ion Collider.

      $**$ In X-ray binaries a neutron star accretes material from its companion. Nuclear burning of accreted material on the surface of a neutron star leads to type-I X-ray bursts, which provide ideal astrophysical laboratories to study the properties of neutron stars, and synthesis of elements in the explosive astrophysical environments. New observations from these explosive astronomical events are generating exciting new challenges for nuclear physics and force a rethinking of old paradigms. To decode observations from X-ray binaries, new nuclear data on very exotic nuclei is required, e.g., nuclear reaction rates or detailed nuclear structure/properties of exotic nuclei. Facility for Rare Isotope Beams (FRIB), a newly developed world’s leading radioactive ion beam facility, will provide an unprecedented access to the very exotic proton-rich and neutron-rich nuclei. In this talk, I will highlight the need for new nuclear physics data to decode observations from X-ray binaries and how FRIB is opening a new window to explore the most exotic nuclei on earth, to provide much-needed data to facilitate model-observation comparison.

2024-2025 Committee