Physics & Astronomy

Coffeeshop Astrophysics - Space Rocks and Stardust
2025-11-15 13:00 - 15:00 (America/Chicago) | Anodyne Coffee Shop, 224 W Bruce Street, Milwaukee, WI, United States
Space Rocks and Stardust
Speakers: Pratyasha Gitika, Tamal RoyChowdhury, Laila Vleeschower
Are shooting stars really stars falling from the sky? Spoiler alert: they’re not! Those quick flashes of light are actually tiny bits of space dust and rock burning up in our atmosphere. In this talk, we’ll take a journey through the leftovers of the formation of our Solar System: asteroids, meteorites, and comets. We’ll talk about how these cosmic “crumbs” sometimes light up our skies as meteor showers, how a rock you could hold in your hand might be older than the Earth itself, and how one very big space rock may have changed the path of life’s evolution on Earth by wiping out the dinosaurs.
More information is available on the Coffeeshop Astrophysics website.

CANCELLED: Physics Colloquium - Jong-Woo Kim
2025-11-14 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Due to circumstances beyond our control, the Physics Colloquium for Friday, 11/14/2025 has been cancelled.
Jong-Woo Kim, Argonne National Lab

CGCA Seminar - Terrence Pierre Jacques
2025-11-14 13:00 - 14:00 | Kenwood IRC 2175, Milwaukee, WI, 53211, United States
Self-Consistent Simulations of the Bar-mode Instability in Rotating Quasi-Stable Neutron Stars
Dr. Terrence Pierre Jacques
West Virginia University
Rapidly rotating neutron stars (NSs) formed from core-collapse supernovae serve as excellent astrophysical laboratories for probing their equation of state (EoS) and internal structure. As these stars cool and contract, their spin angular momentum may increase, making them susceptible to the dynamical bar-mode instability. Once this instability sets in, these stars experience a redistribution of matter and angular momentum, producing gravitational waves that may be detectable by future observatories.
In this talk, I will describe the numerical techniques used to model these quasi-stable NS configurations and demonstrate how gravitational wave signals produced from simulations can be used to constrain the NS EoS.

CANCELLED: Physics Colloquium - Justin Goodrich
2025-11-07 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Due to circumstances beyond our control, the Physics Colloquium for Friday, 11/7/2025 is cancelled.
Justin Goodrich, Brookhaven National Laboratory

CGCA Seminar - Dr. Amy Steele
2025-11-07 13:00 - 14:00 | Kenwood IRC 2175, Milwaukee, WI, 53211, United States
Dr. Amy Steele, Planetary Science Institute
The CGCA Friday Seminar Series is hosted by the Center for Gravitation, Cosmology & Astrophysics at the University of Wisconsin-Milwaukee. These seminars cover a broad number of topics related to the Center’s research areas. Talk titles and abstracts will be posted when available.

Physics Colloquium - Pratyusava Baral
2025-10-31 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Detecting & Measuring Gravitational Waves in Current and Future Observatories
Pratyusava Baral
Graduate Student
University of Wisconsin-Milwaukee
Low-latency (near real-time) detection of gravitational waves (GW) is crucial for multimessenger astronomy. I contribute to maintaining and operating the GstLAL-based search pipeline, a flagship detection pipeline used by the LIGO-Virgo-KAGRA collaboration, for the present observing run (May 2023 – ongoing). To test low-latency performance, mock data challenges (MDC) are designed. I studied the latencies of sending out public alerts, used to communicate with astronomers, after a detection using the MDC. I also demonstrated the feasibility of a neural network-based algorithm that identifies the event with the best skymap for multimessenger follow-up from a set of several GW triggers in low latency.
Looking forward to next-generation detectors such as Cosmic Explorer (CE), I developed the first Bayesian framework to estimate errors on inferred parameters, incorporating effects due to Earth’s rotation and the long arm-lengths of the detectors. These effects are important for next-generation detectors and can be used to localize sources on the sky. This framework can analyze long and loud signals in ~1 day and is capable of using waveforms containing higher modes of radiation.

Coffeeshop Astrophysics - Nebulae: From Cradle to Grave, and Cradle Again
2025-10-25 13:00 - 15:00 | Anodyne Coffee Shop, 224 W Bruce Street, Milwaukee, WI, United States
Nebulae: From Cradle to Grave, and Cradle Again
Speakers: Calvin Dear, Jason Vazquez, Caleb Ogle
Have you ever looked at a stunning picture from NASA full of swirling colors, almost like it should be hanging in an art museum? Chances are, you’re looking at a nebula. Nebulae are enormous clouds of dust and gas out in space. Some nebulae are the aftermath of a supernova, the explosive death of a massive star. Others serve as the birthplace of many new stars, formed by the gravitational pull of gas and radiative push of their first stars. Some nebulae even act as both. Join us as we explore nebulae and their role in star formation, and of course, look at many breathtaking pictures.
More information is available on the Coffeeshop Astrophysics website.

Physics Colloquium - Amanda Baylor
2025-10-24 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Early Warning of Gravitational Waves from Neutron Star Mergers
Amanda Baylor
Graduate Student
University of Wisconsin-Milwaukee
For the past decade, ground-based gravitational-wave observatories have been making detections of ripples in the fabric of spacetime from the mergers of black holes and neutron stars. Mergers involving at least one neutron star could also produce electromagnetic counterparts which may reveal new insights into the physics of these astrophysical phenomena. However, if electromagnetic observatories are not pointed at the location of the source prior to merger, we miss vital information about the physics of merger. This presents a need for early-warning alerts, which are alerts that are sent to observatories once a gravitational wave has been detected but before the objects collide and merge.
This talk will provide an overview of gravitational-wave physics from detection to data analysis and discuss the prospects for early-warning detection of neutron star mergers.

CGCA Seminar - Usha Raut
2025-10-17 13:00 - 14:00 | Kenwood IRC 2175, Milwaukee, WI, 53211, United States
Prof. Usha Raut, Milwaukee School of Engineering
Can LIGO be Relevant for High Energy Physics?
There have been spectacular advances by LIGO, and other gravitational wave detectors in recent years. But an obvious limitation is that gravitational wave detectors currently in operation mostly deal with frequencies below 10 kHz. At the same time, it is generally accepted that there could be very promising physics still to be discovered at higher frequency scales of the gravitational wave spectrum. This can be understood better when we consider the vast frequency ranges that have been discovered for the electromagnetic spectrum and the incredibly useful applications that have been found for high frequency x-rays and gamma rays.
Therefore, a major goal of this presentation is to get a dialogue started on the possibility of a LIGO expansion to high and ultra-high frequencies of the gravitational wave spectrum within a laboratory setting, without necessarily relying on astrophysical or cosmological sources.
The CGCA Friday Seminar Series is hosted by the Center for Gravitation, Cosmology & Astrophysics at the University of Wisconsin-Milwaukee. These seminars cover a broad number of topics related to the Center’s research areas. Talk titles and abstracts will be posted when available.

CGCA Public Talk - Searching for Life in the Universe
2025-10-15 18:30 - 20:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Searching for Life in the Universe
Presented by Dr. Dawn Erb
We hope you will join us on Wednesday, October 15 in the new Chemistry Building, Room #108 for Dr. Dawn Erb’s presentation, “Searching for Life in the Universe.”
This is a free event! Doors open at 6:30 pm with cookies and dessert bars as well as a cash bar. The program will start at 7:00 pm.
Please reserve your free spot for this event. More information is available on the CGCA website.
Due to construction, we recommend you use the parking garage under the Lubar College of Business, located at 3202 N. Maryland Ave. This is a full pay garage that offers ADA parking options near the entrance. You will pull a ticket to enter and pay upon exit. You will find the Chemistry Building by walking south on Maryland to the crosswalk. Head west using the crosswalk on the corner of Maryland Ave. and Kenwood Blvd. The new Chemistry Building is just a half a block, with entrances on Kenwood Blvd. Please be sure to note the restrictions on parking signs if you choose to park on the street.
ADA parking spaces are also available in the front of the Chemistry Building. You will need to pay for parking through the MKE Park Mobile app by using code 59043 which will allow extending the parking session past the 30 minutes limit on the Chemistry circle signs. The hourly rate is $0.80/hour.
Lastly, if you don’t wish to use a parking app, you can call UWM Transportation Services at 414-229-4000 on the day of and pay for parking over the phone. They will collect payment via a credit/debit card. They will ask for your license plate information and email if you would like a receipt. The office is open until 4:30 pm weekdays.
We look forward to seeing you there!

CGCA Seminar - Hector Silva
2025-10-10 13:00 - 14:00 | Kenwood IRC 2175, Milwaukee, WI, 53211, United States
Prof. Hector Silva, Assistant Professor at the Department of Physics of the University of Illinois Urbana-Champaign
The ringing of a different bell: quasinormal modes and their excitation beyond general relativity
The inference of quasinormal mode frequencies from the ringdown part of gravitational-wave signals produced by the coalescence of black hole binaries can be used to infer the mass and spin of the remnant black hole and, possibly, test general relativity and extensions thereof in the strong-field regime. In this seminar, I will share some findings of a long-term project aimed at studying the quasinormal-mode spectrum of black holes beyond general relativity, and how these modes are excited given an initial perturbation. I will interpret these findings from an effective-field-theory perspective, and discuss some (a priori!) surprising consequences.
The CGCA Friday Seminar Series is hosted by the Center for Gravitation, Cosmology & Astrophysics at the University of Wisconsin-Milwaukee. These seminars cover a broad number of topics related to the Center’s research areas. Talk titles and abstracts will be posted when available.

Coffeeshop Astrophysics - The View from Above
2025-09-27 13:00 - 15:00 | Anodyne Coffee Shop, 224 W Bruce Street, Milwaukee, WI, United States
The View from Above
Speakers: Leith Benali, Lulu Agazie
Since the launch of Sputnik 1 in 1957, roughly 14,500 satellites have been launched into orbit around Earth. Currently there are about 11,700 active satellites, roughly 1,100 of which are used for Earth science. These are very powerful tools for studying large scale phenomena on Earth that are hard to observe from Earth’s surface. In this talk we’ll talk about how scientists use satellite observations for doing research on everything from weather patterns and tectonic plate movement to air pollution and environmental disasters.
More information is available on the Coffeeshop Astrophysics website.

Physics Colloquium - Justin A. Trujillo
2025-06-25 13:00 - 14:30 | Kenwood IRC 2175, Milwaukee, WI, 53211, United States
Speaker: Justin A. Trujillo, PhD Candidate – UWM Physics
Implementing Novel Data Analysis Methods to Enhance Biophysical Studies
Studying the structure, motions, and interactions of proteins as they perform their functions is greatly important in biophysics research. Time-resolved serial femtosecond crystallography (TRSFX) has been highly successful at resolving protein structures and motions. However, TR-SFX data can be challenging to analyze. To address this, we used a machine learning algorithm and applied it to simulated diffraction data for photoactive yellow protein (PYP). The results show that the machine learning method successfully recovers structural and dynamical information, demonstrating that this method can be trusted for crystallography and other complex datasets.
Another method for studying proteins is fluorescence microscopy paired with Förster resonance energy transfer (FRET). Being highly sensitive to separation distance between fluorescent molecules, FRET is a precise way to study protein interactions in cells. The quantity of interest in these studies is the FRET efficiency, which measures energy transfer via FRET between fluorescent molecules. FRET efficiencies calculated from spectrally resolved data allow for the quaternary structure of proteins to be studied using a method known as FRET spectrometry. However, due to constraints with interpreting data, this capability has not been used with time-resolved data. In the second part of this work, we show the results of implementing a novel method of extracting FRET efficiencies from time-resolved data. This new approach may expand FRET spectrometry to be compatible with time-resolved data.
Location: Kenwood IRC 2175
Time: 1:00PM – 2:30PM
Date: June 25th, 2025

Physics Colloquium - Katey Alatalo
2025-05-09 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Speaker: Dr. Katey Alatalo, Assistant Astronomer, Space Telescope Science Institute
The Life-cycle of Gas in Dying Galaxies
Modern day galaxies populate a bimodal distribution, in both morphology and color space. Their morphological and color properties are also inter-related, with lenticular and elliptical galaxies exhibiting red colors and spiral galaxies usually exhibiting blue colors. In color space, there is a genuine dearth of intermediate colored galaxies, suggesting that the transition a galaxy undergoes to transform must be rapid, and quenching galaxies, rare. Gas – its presence, absence, and mechanics – serves as the anchor of a galaxy’s transformation from blue to red.
I will discuss the nature of gas in transitioning and transitioned galaxies through two lenses: (1) How a galaxy transition is able to impact the behavior of molecular gas, and (2) how new observations of molecular gas in quenching and quenched galaxies has recast our understanding of how they ultimately metamorphose from blue, star-forming spirals into red, quiescent ellipticals and lenticulars.
Location: Chemistry 108
Time: 3:30PM – 5:00PM
Date: May 9th, 2025

Physics Colloquium - Sukanya Chakrabarti
2025-05-02 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Speaker: Sukanya Chakrabarti, Ph. D., Pei-Ling Chan Endowed Chair and Professor, School of Physics and Astronomy, University of Alabama-Huntsville
The Precision Frontier of Dark Matter Constraints from Direct Acceleration Measurements
For over a century, our understanding of dark matter has hinged on kinematic estimates derived from static snapshots of stellar positions and velocities. However, these methods are inaccurate for a time-dependent potential, and there are now many lines of observational evidence that show that our Galaxy has had a highly dynamic history. We have now entered an era where we can carry out precision time-series measurements of the accelerations of stars that live within the gravitational potential of our Galaxy.
I will discuss our comprehensive observational strategy to directly measure Galactic accelerations. Central to this discussion is our recent analysis of compiled pulsar timing data from which we were able to measure the Galactic acceleration for the first time, and derive fundamental Galactic parameters. Discernible differences in sub-structure exist among popular dark matter models on small scales, presenting testable nuances. I will discuss the potential for measuring dark matter sub-structure in the Milky Way by leveraging the diverse set of techniques we have developed, including pulsar timing, eclipse timing, and extreme-precision radial velocity observations. I will review our results from our multi-pronged observing campaign, and end by discussing synergies between Galactic dark matter constraints and constraints on theories of gravity.
Location: Chemistry 108
Time: 3:30PM – 5:00PM
Date: May 2nd, 2025

Physics Colloquium – Ned Budisa
2025-04-18 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Speaker: Ned Budisa, Professor & Research Chair, Dept. of Chemistry, University of Manitoba
Expanding the Genetic Code via Directed Evolution: Tools for Biophysicists, Materials Science, and Beyond
Reprogramming the genetic code to include non-canonical amino acids (ncAAs) is a powerful tool in systems bioengineering that combines synthetic biology, chemistry, biophysics, and genome manipulation. This approach enables enhanced protein biosynthesis, deeper insights into translation, and the creation of novel functionalities and new-to-nature proteins and other foldamer-scaffolds. Expansion of the genetic code results in proteins and cells with new properties, including site-specific functionalization through various bioorthogonal chemistries.
At the heart of this endeavor are aminoacyl-tRNA synthetases (aaRS), whose modified forms – paired with cognate tRNAs – form orthogonal translation systems (OTS) for precise incorporation of ncAAs, often via amber stop codons. Directed evolution under selective pressure is used to remodel the active aaRS center to accept specific ncAAs. Traditional gene libraries focus on the first-shell residues (<6 Å) and are constrained by the transformation limits of E. coli (~10⁸–10⁹ variants), often neglecting second-shell interactions (<9 Å). To overcome this, computational enzyme design and novel wet-lab strategies are driving the evolution of effective binding pockets and cellular compatibility with exotic chemicals.
I will illustrate these approaches using (i) directed evolution of enzyme pockets, (ii) adaptive laboratory evolution of the amino acid repertoire, and (iii) genomic integration of orthogonal translation machineries for synthetic cell design.
Finally, I will provide an overview of ncAAs that are valuable for biological spectroscopy and microscopy. These site-specifically incorporated ncAAs serve as vibrational, fluorescent, EPR, or NMR probes in cellular, organismic, and in vitro contexts. Over the last two decades, their use has provided unprecedented insights into protein structure and dynamics. Bioorthogonal reactions – in particular Click Chemistry – provide powerful tools to introduce labels or mimic post-translational modifications. Applications now include capturing transient interactions, tuning protein function and generating therapeutic agents such as covalent peptides and site-specific labeled antibody conjugates.
Location: Chemistry 108
Time: 3:30PM – 5:00PM
Date: April 18th, 202

Physics Colloquium – Gabriel Freedman
2025-04-17 10:00 - 12:00 | KIRC KEN 2175, 3135 N. Maryland Ave., Milwaukee, 53211
Speaker: Gabriel Freedman, PhD Candidate – UWM Physics
Low-frequency Gravitational Wave Searches and Data Analysis with Hamiltonian Sampling
The pulsar timing array community has found evidence for a correlated stochastic signal following the Hellings-Downs pattern indicative of an isotropic stochastic gravitational-wave background (GWB). The most likely source of such a background is a population of supermassive black hole binaries, and particularly loud individual sources could be detected in future datasets.
We present work done towards performing joint Bayesian searches for both the GWB and single sources utilizing the Hamiltonian Monte Carlo sampling algorithm to efficiently explore these complex parameter spaces. We end by discussing applications of these methods to data analysis for the upcoming Laser Interferometer Space Antenna mission.
Location: Kenwood IRC 2175
Time: 10:00AM – 12:00PM
Date: April 17th, 2025

Physics Colloquium - Sheng Ran
2025-04-11 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Sheng Ran, Assistant Professor of Physics, Washington University
Strongly Correlation and Topology in Kondo Lattice Systems
Quantum materials with both strong correlations and nontrivial band structure topology can have novel physics properties that do not exist in the non-correlated counterparts. Recent theoretical work has demonstrated that combination of Kondo physics and nonsymmorphic crystal symmetries can give rise to such strong correlated topological systems.
In this talk, I will present our recent experimental exploration this direction. In one case, we found intrinsic anomalous Hall effect that seems to break the Fermi liquid scaling relation. In another case, we have discovered a candidate for topological Kondo insulator.
The event flyer is available here.

Physics Colloquium - Shaswat Sardesai
2025-04-04 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Shashwat Sardesai, PhD Candidate, UWM Physics
Cosmic Orchestra: The Gravitational Wave Background
In the last year and a half, the North American Nanohertz Observatory for Gravitational Waves, and their collaborators, have detected the presence of a gravitational wave background using pulsar timing arrays. These gravitational waves likely arise from supermassive black hole binaries (SMBHBs) and have periods spanning years or decades.
In this talk, I will go over the basics of PTAs, the different methods to analyze the background, as well as the projects I have worked on as a member of the NANOGrav collaboration to try and resolve aspects of the GWB.
The event flyer is available here.

Spring 2025 APS Preview Talks
2025-03-14 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
UWM Physics Post docs, graduate student, and faculty
Spring 2025 APS Preview Talks
Members of the UWM Physics department will present their preview talks in preparation for the upcoming APS meetings
The event flyer is available here.

Physics Colloquium - David Hogg
2025-02-28 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
David Hogg, Professor of Physics & Data Science, NYU
Sailing as Momentum Transport
Sailboats represent an ancient (but newly relevant) sustainable form of transportation. They work off the relative velocity between the air and the water. Sailboats can sail upwind (by tacking), they can sail downwind faster than the wind (also by tacking), and they can sail crosswind much faster than the wind.
I present the simplest possible momentum transport model of a sailboat, and explain all of these capabilities. In this (spherical scow) model, the sailboat is defined by three dimensionless numbers: the sail-to-keel area ratio, a lift ratio for the sail, and a lift ratio for the keel. The model makes a number of amusing “predictions” that explain the properties of commercial and competitive sailboats. There are many connections to sustainable energy.
The event flyer is available here.

Physics Colloquium - Geoffrey Bower
2025-02-21 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Geoffrey Bower, Chief Scientist for Hawaii Operations, Academia Sinica Institute of Astronomy and Astrophysics, Project Scientist, Event Horizon Telescope Collaboration, Affiliate Graduate Faculty, University of Hawaii-Manoa, Dept. of Physics and Astronomy
Imaging Black Holes with the Event Horizon Telescope
The Event Horizon Telescope (EHT) is a global submillimeter-wavelength very long baseline array that produces the highest angular resolution images of black holes. The EHT Collaboration has produced images of two black holes, the supermassive black hole in the elliptical galaxy M87 and the Galactic Center black hole, Sgr A*.
In this talk, I will describe the techniques and technology behind these measurements, give updates on the latest results, and plans for future observations. Images of both sources have a ring-like morphology consistent with predictions of general relativity and the Kerr metric. Comparison with an unprecedented library of GRMHD simulations provides insights on the accretion and outflow properties. These results confirm that the gravitational lensing feature is a universal property of black holes, establishes the consistency of general relativity over three orders of magnitude in mass, and opens the door for future tests of gravitational physics, accretion, and jet formation.
The event flyer is available here.

Physics Colloquium - Scott Hertel
2024-12-13 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Scott Hertel, Assoc. Professor, Dept. of Physics, University of Massachusetts-Amherst
Recent Progress Towards the Detection of Dark Matter
As you read this, you are immersed in a bath of particles beyond the Standard Model, so-called ‘dark matter’ particles which are noticed only through their gravitational effects at astrophysical scales. Discovering the properties of these unseen particles (their mass, interactions with other particles, etc.) is one of the great challenges of 21st century physics.
I will describe two complementary efforts which search for individual dark matter particles in a laboratory setting here on earth: LZ and TESSERACT. Each effort search Centeres for the individual scatters of galactic dark matter particles with atoms here on earth, and each effort requires the development of novel and interesting technologies. I will update you on our progress towards unraveling this great mystery of physics.
The event flyer is available here.

Physics Colloquium - Professor Scott A. Hughes
2024-12-06 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Professor Scott A. Hughes, Dept. of Physics & the Kavli Institute, MIT
High-precision Waveforms with the Small-mass-ratio Limit
Current gravitational-wave detectors are being upgraded, and plans are developing for future detectors with greater sensitivity over broader frequency bands. As instruments improve and develop, more cycles of sources’ gravitational waveforms will be measured with greater signal to noise ratio. Such higher fidelity measurements promise to teach us more about their sources and the nature of strong-field gravity — but only if theoretical modeling of these waves is able to match advances in the detectors. As we measure waveforms with better precision, the likelihood increases that systematic modeling errors will affect inferences about what we measure.
In this talk, I will survey recent progress modeling waveforms from small-mass binaries. Such binaries, which exactly describe important low-frequency gravitational wave sources, also serve as a limit of the more general binary problem that can be modeled with very high precision. I will discuss the outstanding progress that has been made on this problem in recent years, and how what we learn in this limit can be combined with other binary modeling techniques to advance modeling for relativistic binaries in general.
The event flyer is available here.

Physics Colloquium - Dr. Joshua "Shua" Sanchez
2024-11-22 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Dr. Joshua “Shua” Sanchez, Postdoctoral Fellow, Department of Physics, MIT
Quantum Criticality and Magnetic Field-Induced Superconductivity
When electrons have strong interactions with each other, new quantum phases of matter emerge, such as magnetism, nematicity, charge order, and superconductivity. In these “Quantum Materials”, the microscopic interactions can be very difficult to probe and understand, yet they give rise to macroscopic properties that are easier to study and can be harnessed for new technologies.
In this talk, I will demonstrate how synchrotron x-ray techniques can be powerful probes to study the mysterious origin of strongly-correlated phases. I will discuss several recent projects at the Advanced Photon Source at Argonne National Laboratory, using a novel sample characterization platform that simultaneously combines x-rays, in-situ structural tuning, applied magnetic field, and electrical transport measurements. Our work yields new insights on two broad questions in high-temperature iron-based superconductors. (1) How does quantum criticality and nematicity relate to unconventional superconductivity? and (2) How can ferromagnetism and superconductivity coexist in one material, and how do they affect each other?
References:
(1) Sanchez, et al. Nature Materials 20, 1519–1524 (2021)
(2) Sanchez, et al. Science Advances 9, eadj5200 (2023)
The event flyer is available here.

Physics Colloquium - Catalin Picu
2024-10-18 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Catalin Picu, Dept. of Mechanical, Aerospace & Nuclear Engineering, Rensselaer Polytechnic Institute
Soft Network Materials: Structure-Properties Relations
Many materials have a stochastic network of filaments as their main structural component and are referred to collectively as ‘network materials.’ This class includes all biological connective tissue, the extracellular matrix, the intra-cellular cytoskeleton, paper and cellulose-based products, nonwovens, as well as various molecular networks such as rubber, gels and thermosets.
This talk reviews the relation between the structure of athermal networks and the material-scale mechanical properties, focusing on identifying commonalities between these very diverse material systems. Properties of interest include the non-linear elastic response, the viscoelastic response, strength and toughness. The effect of inter-fiber adhesion on network mechanics will be also discussed. The talk provides a comprehensive overview of the mechanics of this broad class of materials.
The event flyer is available here.

Physics Colloquium - Hongbin Li
2024-10-11 15:30 - 17:00 | Chemistry 108, 2050 E Kenwood Blvd, Milwaukee, WI, 53201, United States
Hongbin Li, Professor, Department of Chemistry, The University of British Columbia
Rational Engineering of Protein-based Biomaterials: from single molecule traits to functional material properties
In their biological settings, elastomeric proteins function as molecular springs, thereby establishing elastic connections, plus providing mechanical strength and elasticity. With an ability to change their shape (evolving from simple, random coil-like structures to a more sophisticated beads-on-a string formation), they fulfill their biological function. These complex protein polymers exhibit distinct mechanical properties.
The development of single molecule force spectroscopy techniques has made it possible to directly probe these properties, at the single molecule level, allowing us to understand their molecular design principles. This knowledge has enabled us to engineer novel elastomeric proteins to achieve tailored and well-defined nanomechanical properties.
In this talk, specific examples will be given on engineering protein hydrogels to mimic the passive elastic properties of muscle, as well as highly stiff and highly tough protein biomaterials to mimic the mechanical properties of cartilage. These studies will pave the way to utilizing proteins as building blocks to engineer new generations of protein-based biomaterials for diverse applications in biomedical engineering as well as material sciences.
The event flyer is available here.

Physics Colloquium - Segev BenZvi
2024-05-03 15:30 - 17:00 | KIRC 1150, 3135 N. Maryland Ave., Milwaukee, WI, 53211, United States
Segev BenZvi, Assoc. Professor, Department of Physics, University of Rochester
Measuring Cosmic Expansion with the Dark Energy Spectroscopic Instrument
Since the first observations of the accelerating expansion of the universe at the end of the 1990s, astronomers and physicists have struggled to understand dark energy, a mysterious repulsive force that drives the acceleration. A number of models of dark energy exist. The simplest (the cosmological constant), assumes dark energy is non-interacting and is the same everywhere in space and time. Different models predict subtely different features in the large-scale structure of the universe. We are now entering an era of new photometric and spectroscopic surveys which can discriminate different models of dark energy with unprecedented precision.
In this talk, I will present the latest results from the Dark Energy Spectroscopic Instrument (DESI), a fiber-fed, robotically-actuated galaxy redshift survey that has been in operation at Kitt Peak National Observatory since mid-2021. In April 2024, the DESI Collaboration released its results from the first year of data taking. I will describe the performance of DESI, summarize the first year of data and our cosmological analyses, and present prospects for future results.
The event flyer is available here.

Physics Colloquium - Rob Pisarski
2024-04-26 15:30 - 17:00 | KIRC 1150, 3135 N. Maryland Ave., Milwaukee, WI, 53211, United States
Rob Pisarski, Distinguished Scientist, Department of Physics, Brookhaven National Laboratory
The Ugly Duckling and the Swan: The Quark-Gluon Plasma and Heavy Ion Collision
I give a pedagogical and historical overview of the search for the Quark-Gluon plasma (QGP) in the collisions of heavy ions. I begin with a brief review of why we expect a QGP to be formed at high temperature. In this, numerical simulations in lattice Quantum ChromoDynamics (QCD) form the bedrock of the field. In particular, they demonstrate the relationship between deconfinement and the restoration of chiral symmetry.
At the SPS at CERN, I discuss the suppression of J/Psi mesons, and the excess of dileptons below the rho meson. Bjorken first noticed that a “plateau” may emerge at high energies, and produce a regime at high temperature, and low chemical potential. At colliders such as RHIC, at Brookhaven, and the LHC, at CERN, I discuss two notable signals: the utility of nearly ideal hydrodynamics, and jet quenching. The new frontier is going down to moderate collision energies, which there is net excess of baryons. Possible phenomena in this region include a critical end point and moat regimes.
The event flyer is available here.

Physics Colloquium - Joel Nowitzke
2024-04-19 15:30 - 17:00 | KIRC 1150, 3135 N. Maryland Ave., Milwaukee, WI, 53211, United States
Joel Nowitzke, PhD Candidate, UW-Milwaukee
Modeling and Measurements of Network Formation and Viscoelastic Behavior of Folded Protein-Based Hydrogels
Proteins are vital for various daily functions and are even used in creating biocompatible materials through chemical crosslinking. However, predicting the mechanical properties of these materials is challenging due to the random orientation of constituent molecules within the network. Bridging the gap between nanoscopic and macroscopic scales is essential for formulating predictable biomaterials. Through a combination of experimental methods and computational simulations, including Single Molecule Magnetic Tweezers and Steered Molecular Dynamics Simulations, we aim to understand these properties. This approach involves determining the relative stability of pulling geometries and simulating protein unfolding to create accurate models. By subjecting simulated networks to external stress, we assess their behavior compared to experimental data, ensuring realistic predictions.
The event flyer is available for download here.
