Physics Colloquium Fall 2025

Thursdays 4:00 p.m. 104 Physics.
Colloquium organizer: Dr. Simeon Mistakidis smystakidis@mst.edu

Watch past colloquia on our YouTube Channel


(Link to main colloquium page)

Title: Soliton and Vortex Patterns: From BECs to Quantum Droplets & Beyond 

Abstract: In the present talk, I will start from an overview of earlier studies in 1-component and 2-component atomic Bose-Einstein condensates driven from experimental developments over the past 15 years that have led to a systematic understanding of the motion of quasi-one-dimensional dark solitons (DS) and quasi-two-dimensional vortex solitons (VS) in such settings. The evolution of single DS and VS in trapped environments and the pairwise interaction of multiple such structures and their comparison with numerical computations and experimental data will be presented. Then, we will move to a more recent generation of experiments capturing the role of quantum fluctuation induced corrections. The mathematical challenges that these recent experiments pose at the level of competition of focusing and defocusing nonlinearities will be highlighted, some opportunities at the level of the creation of novel structures (droplets, bubbles, kinks, etc.) will be explored and finally some intriguing mathematical features, such as the transverse stability in higher dimensions of kinks will be discussed. 

Title: Vortices and vortex rings in quantum superfluids: a quasi-particle approach

Abstract: Motivated by recent experiments studying 2D vortex dynamics in Bose-Einstein condensates (BECs), we illustrate that, by considering these vortices as quasi-particles, such systems can be accurately described by reduced models of coupled ordinary differential equations. It is then possible to study in detail the dynamics, stability, and bifurcations of vortex configurations and match the ensuing results to experimental observations. We will also explore some extensions of the quasi-particle approach for 3D vortex rings which are formed when a vortex line (a "twister") is looped back onto itself creating a close ring that carries vorticity. We first showcase how vortex rings are commonplace in a wide range of fluids. We then focus on the occurrence of vortex rings in BECs and their mutual interactions, collisions, and scattering scenarios.

Title: Electronic properties of unconventional magnets

Abstract: In addition to conventional magnets such as ferromagnets and antiferromagnets, unconventional magnets, such as altermagnets and p-wave magnets, have recently received significant attention. These unconventional magnets have even- and odd-parity spin polarizations in their electronic band structures while maintaining zero net magnetization. These band structures allow for rich transport phenomena and interaction effects. In the first part of the talk, I will show that despite the absence of bulk magnetization, the itinerant electrons in altermagnets can generate local magnetization close to interfaces and impurities. The second part of my talk will focus on p-wave magnets. I will present the derivation of the effective model of these systems and discuss its implications for tunneling magnetoresistance, transport, and superconductivity. These results expand our understanding of magnetism and contribute to the development of spintronics and quantum material research.

Dr. Hasti Khoraminezhad. Title: Simulating Realistic Lyman-α Emitters Including the Effect of Radiative Transfer 

Dr. Yanyan Zheng. Title: Detecting gravitational waves from core-collapse supernova

Dr. George Bougas. Title: Generation of Peregrine solitons in multi-component Bose-Einstein condensates

Dr. Amit Kumar. Title:  Evolution of satellite galaxies in dense environments

Title: Probing Cosmic Acceleration with Galaxy Clusters

Abstract: Our understanding of the Universe is at a critical juncture.  For decades, the standard model of cosmology based on general relativity, dark matter, and constant dark energy (ɅCDM) has passed many experimental tests.  However, the recent hint of evolving dark energy — with the possibility of a phantom dark energy — has the potential to challenge ɅCDM.  In this talk, I will discuss how we use galaxy clusters to measure the evolution of structure and to probe the nature of gravity at cosmological scales.   I will talk about how we use observations across the electromagnetic spectrum to understand the astrophysics of clusters, which in turn makes clusters better cosmological probes.  I will also discuss how we plan to combine galaxy clusters with other cosmological probes to measure the nature of dark energy.

Physics Beyond the Lab: Building Wonder Through Museums

How does a physics degree from Missouri S&T lead to building science museums that inspire millions? In this homecoming colloquium, Dr. Ray Vandiver shares his journey from Rolla to a lifelong career in science museums—an unexpected path pioneered by physicist Frank Oppenheimer. Drawing on more than three decades of leadership in museum design and education, Ray will reflect on how physics shaped his work, highlight his new role as President & CEO of the Saint Louis Science Center, and offer a look at what’s ahead for one of the nation’s leading science centers.

From Silence to Sound: 10 Years of Gravitational Waves from Colliding Black Holes
On September 14, 2015, at 4:50:45 a.m. Central US time, the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a gravitational-wave signal that originated 1.3 billion light-years ago in a faraway galaxy. The source of the gravitational wave was a cataclysmic collision of two massive black holes releasing so much energy that it rippled the fabric of space
and time across the entire universe. Gravitational waves were predicted by Albert Einstein a century ago and were believed to be undetectable. And yet the human ingenuity of thousands of researchers, engineers, and technicians, and the vision of a few of the greatest scientists of our time, brought us a discovery that ``shook the world'' and created a completely new branch of science to reveal the deepest secrets of the dark universe. As we celebrate the tenth anniversary of one of the most important scientific achievements of this century, observations of gravitational waves from colliding black holes have become routine. In this talk, we will revisit the excitement surrounding the initial discovery, explore the science of gravitational waves and black holes, examine current results, and discuss the expectations for gravitational-wave astrophysics over the next decade.

Title: Topological Quantum Materials Prepared by Epitaxy
Abstract:
Topological quantum materials represent a new frontier of condensed matter physics. Their unusual electronic structures give rise to boundary states that are remarkably robust—properties that could enable future advances in quantum computing, spin-based electronics, and photonic technologies.
In this talk, I will describe our efforts to create and control such materials using molecular beam epitaxy, a technique that allows us to build crystals one atomic layer at a time. Two systems are of particular interest: elemental tin (Sn) and the alloy Bi1-xSbx. Sn is especially intriguing because it can exist in two distinct structural forms—α-Sn, which behaves as a topological material, and β-Sn, which is a superconductor. By carefully adjusting lattice strain, we can switch between these phases and explore how their electronic properties evolve. The Bi1-xSbx system offers an even richer landscape, hosting a variety of topological phases depending on its composition and
thickness. In thin films, we observe how reducing the layer thickness can drive a transition from metallic to insulating behavior—a hallmark of quantum confinement.
Together, these studies reveal how precise control of composition, strain, and dimensionality enables us to design and tune quantum states of matter. I will conclude by showing how these materials can be patterned into nanowires and combined with superconductors, opening exciting possibilities for realizing new forms of quantum devices.

Title: Making Gravitational Wave CoCoA: A Recipe for Unraveling the Post-Merger Mystery of Gamma-Ray Bursts

Abstract: The multi-messenger detection of GW170817 and its associated Gamma-Ray Burst (GRB) 170817A stands as a landmark achievement – yet it remains our one and only confident multi-messenger observation to date. Moreover, numerous GRB emission models predict post-merger gravitational wave emission on "intermediate" timescales lasting hundreds to thousands of seconds, yet none of our benchmark search pipelines are well-equipped to analyze this signal regime. To address this gap, we have developed the Cross Correlation Algorithm (CoCoA), which unifies modeled and un-modeled search techniques into a single framework optimized for detecting these elusive signals. In this talk, I will describe our efforts to search for gravitational wave emission associated with GRBs detected during LIGO-Virgo-KAGRA observing runs, the technical innovations that make CoCoA sensitive to signals traditional methods miss, and our progress toward the next multi-messenger breakthrough.

Molecular physics without molecules in flat-band quantum materials

 

We all are familiar with molecular states in stable clusters of atoms called molecules (H2, H2O, C₈H₁₀N₄O₂, etc.) that form as quantum superpositions of the atoms’ individual wavefunctions. Their energies can be lower than those of the participating atomic states (commonly referred to as orbitals) which gives rise to chemical bonding, the cornerstone phenomenon in the chemical and biological sciences. Surprisingly, certain non-trivial quantum interference effects can lead to the formation of molecular orbital (MO) like states in inorganic crystalline solids without identifiable molecular clusters in their crystal structure. When involved in low-energy physics, MOs often give rise to intriguing physical effects such as flat bands in the electronic structure, expanding experimentally accessible regions of quantum phase diagrams and providing new ways to tune material properties. In this talk, I will present two examples of quantum MO systems: (1) Ti4MnBi2, a one dimensional metallic spin-½ system, and (2) La3Ni2O7, a member of the most recently discovered Ni-based family of high-temperature superconductors. Using these examples, I will attempt to not only illustrate the rich physics of MOs in action but also highlight the challenges that such systems pose at various levels of condensed matter theory.

Title: Witnessing quantum correlations and entanglement in materials 

Abstract: Entanglement and other nonclassical correlations are ubiquitous in quantum many-body systems. This is well-established in quantum information applications, where they represent resources to be harnessed for quantum operations. However, they also play a prominent role in theories of important condensed matter phenomena, such as novel phases of matter. Yet there has been a distinct lack of viable methods to detect these correlations in the solid state, impeding our ability to identify suitable materials and to unravel their secrets. In this talk I will describe the rapid progress made in recent years towards finding useful measures of these properties, which can both be modeled theoretically and measured experimentally in a model-independent fashion, by making use of information “hidden” in spectroscopic data. By employing entanglement witnesses—quantities that are akin to order parameters for certain classes of entangled states—multipartite entanglement has now been observed in quantum spin systems and strongly correlated electron systems. Such quantum information-informed approaches offer new quantitative insights into many-body states and can provide hints for modeling of enigmatic states in quantum materials. 

Title: Cosmic Lighthouses: Pulsars and their Multiwavelength Radiation 

Abstract: Pulsars are rapidly rotating neutron stars that possess the strongest magnetic fields known in the universe. They produce regularly pulsed radiation that spans the entire electromagnetic spectrum, from GHz radio waves up to TeV gamma-rays. The origin of this extremely broadband emission has remained one of the most enigmatic puzzles in astrophysics since their discovery in 1967. In this talk, I will describe how numerical simulations in the past two decades have significantly enhanced our understanding of how pulsars produce their emission. I will also discuss how we can use multiwavelength observations to constrain the physical properties of these stars, from the state of nuclear matter in their interiors to the magnetic structures in their exteriors.