Colloquium

The colloquium is currently held at 4:15 PM on Tuesdays in Harriman 137. Cookies, tea and coffee are served from 4:00 PM outside the lecture hall.

Colloquium committee: Rouven Essig (Chair), Jennifer Cano (Vice Chair), Abhay Deshpande, Will Farr, Harold Metcalf, Jesus Perez Rios, Giacinto Piacquadio

Archive of colloquia from 1999 to the present

Spring 2024 Colloquia

Archived Colloquium Schedules

• Fall 2023 Colloquia

  Date	Speaker	Title & Abstract
  Sep 5	Chang Kee Jung Stony Brook University	Chair's Colloquium
  Sep 12	Chris Greene Purdue University	Universal Physics of 2 or 3 or 4 Strongly Interacting Particles Recent developments in the field of a few interacting particles with nonperturbative interactions will be reviewed, focusing on ultracold atomic and molecular physics, but with one recent application to the few-nucleon problem as well. Some of these studies are intimately connected with the Efimov effect, while others go beyond the standard Efimov effect with its remarkable infinity of long-range energy levels. Some of our relevant references addressing those topics are listed below. [1] Nonadiabatic Molecular Association in Thermal Gases Driven by Radio-Frequency Pulses, Phys. Rev. Lett. 123, 043204 (2019), with Panos Giannakeas, Lev Khaykovich, and Jan-Michael Rost. [2] Nonresonant Density of States Enhancement at Low Energies for Three or Four Neutrons, Phys. Rev. Lett. 125, 052501 (2020), with Michael Higgins, Alejandro Kievsky, and Michele Viviani [3] Efimov physics implications at p-wave fermionic unitarity, Phys Rev A 105, 013308 (2022), with Yu-Hsin Chen. [4] Ultracold Heteronuclear Three-Body Systems: How Diabaticity Limits the Universality of Recombination into Shallow Dimers, Phys. Rev. Lett. 120, 023401 (2018), with Panos Giannakeas.
  Sep 19	Serge Haroche Nobel Prize Recipient, 2012	C.N. Yang Colloquium Click the image below to see the event poster!
  Sep 26	Jan Bernauer Stony Brook University	Exploring the Standard Model with lepton scattering at the precision frontier In the last 100 years, accelerator-based nuclear physics has made incredible advances on the precision frontier: the capability to achieve ever shrinking measurement uncertainties, driven by higher luminosities, better detectors, new experimental techniques, and improved theoretical corrections. This is especially true for lepton scattering, predominantly using electron beams, with a renaissance in positron and muon beams. In this talk, I will cover three topics. First, I will show how such precision measurement can help us understand non-perturbative quantum chromodynamics, focusing on the so-called “proton radius puzzle”, the proton form factors, and the MUSE experiment. Second, I will discuss how one can search for Beyond the Standard Model physics with precision lepton scattering, in the context of the DarkLight@ARIEL measurement and the ATOMKI anomalies. Third, I will explain how Streaming Readout will advance our capabilities for precision measurements.
  Oct 3	Antoine Georges Collège de France, Paris Flatiron Institute, New York	The Diverse Routes to Strong Electronic Correlations: A Dynamical Mean Field Theory Perspective From transition-metal oxides, rare-earth and organic compounds to moiré two-dimensional materials, strong electronic correlations have focused enormous attention over several decades. In this talk, I will emphasize three main mechanisms responsible for strong electronic correlations. The proximity to a Mott insulator, and the Kondo effect leading to heavy fermion behavior have been known for a while. Recently however, it became apparent that the properties of a broad family of materials (including iron-based superconductors) cannot be explained within the Mott or the heavy fermion paradigms. The intra-atomic exchange turns out to be the main player responsible for the properties of these "Hund metals." The classic band theory of solid-state physics must be seriously revised for strongly correlated materials. Instead, a description accounting for both localized atomic excitations and delocalized wave-like quasiparticles is required. I will review how Dynamical Mean-Field Theory (DMFT) fulfills this goal and provides an original physical perspective on strongly correlated electron materials. Thanks to the efforts of a whole community over almost three decades, the theory now provides a practical framework to understand and predict the properties of quantum materials starting from their structure and chemical composition.
  Oct 10	No Colloquium.	Fall Break.
  Oct 17	Gregory Falkovich Weizmann Institute of Science	Zero charge and confinement in turbulence I will describe an attempt to do renormalization in turbulence, considering waves that interact weakly via four-wave scattering (such as sea waves, plasma waves, spin waves, and many others). By summing the series of the most UV-divergent terms in the perturbation theory, we show that the true dimensionless coupling is different from the naive estimate, and find that the effective interaction either decays or grows explosively along the cascade, depending on the sign of the new coupling. The explosive growth possibly signals the appearance of a multi-wave bound state (solitons, shocks, cusps) similar to confinement in quantum chromodynamics.
  Oct 24	Aida El-Khadra University of Illinois Urbana-Champaign	The dance of the muon More than eighty years after the muon was first identified it may serve as a window to discovering new physics. Thanks to new experimental measurements at Fermilab, the muon’s magnetic moment is now known with an exquisite precision of 189 parts per billion, sharpening the longstanding tension between experiment and theoretical expectations. The experimental measurements will continue to improve with the ultimate goal of reducing the experimental uncertainties to 120 parts per billion. The theoretical calculations of the muon’s magnetic moment must account for the virtual effects of all particles and forces within the Standard Model, where effects coming from virtual hadrons, governed by the strong interactions, are by far the largest sources of theory uncertainty. Recent estimates of hadronic corrections have created puzzles on the theory side, which are currently being investigated. I will discuss the ongoing interplay between theory and experiment that is essential to unlocking the discovery potential of this effort.
  Oct 31	Laszlo Forro University of Notre Dame	Status quo in superconductivity Since the groundbreaking discovery in 1911 of a zero-resistance state at 4 K – an outcome then dubbed the "impossible result" – the realm of superconductivity has captivated researchers worldwide. One of the primary aspirations since has been to elevate critical temperatures to ambient conditions, a milestone that would revolutionize energy transport, diagnostics, and information technologies, among other sectors. Recent studies have reported achieving this objective under both extreme pressures and even at standard atmospheric conditions. This colloquium provides a comprehensive overview of the present advancements in superconductivity, including findings from our dedicated research endeavors. See speaker bio here.
  Nov 7	Cyrus Dreyer Stony Brook University	Perfecting quantum imperfections One of the key impacts of condensed-matter physics is its role in predicting, developing, and understanding materials for technological applications, e.g., transistors, light-emitting diodes, and solar cells. In this context, it is not enough to just understand the pristine materials that make up the devices; the imperfections in those materials must also be characterized and understood. In particular, point defects, which are atomic scale imperfections or impurities in the crystal lattice, are ubiquitous in all materials and can have profound effects on their properties and phenomena. Recently, it has been demonstrated that individual point defects are robust and manipulatable quantum systems that can be used as qubits for quantum computing, emitters of single photons for quantum communication, and nanoprobes for quantum metrology. Ab-initio theoretical methods are crucial for understanding defects in both conventional and quantum devices, since their dilute concentration and small size make them difficult to directly characterize experimentally. At the same time, accurate quantitative knowledge of defect properties is necessary to mitigate detrimental defects and utilize beneficial ones. Defects are also challenging for theory as their properties may depend on highly correlated electronic excited states that have complicated coupling to the host crystal lattice. In this colloquium, I will describe new methods we have developed to study quantum defects from first principles, which allow simple but quantitatively accurate models of defect properties to be parametrized and solved. I will give example of how we are using these methods to search and characterize for quantum defects for the next generation of quantum devices.
  Nov 14	Wolf Schäfer Stony Brook University	Robot Ethics and the Plurality of Theories Problem This talk is about a difficulty that emerges when humans build powerful things involving science, technology, and society. My case in point are self-driving cars, i.e., automated vehicles (AVs). Since physicists succeeded in building nuclear bombs, “science has become much too important to be left to the scientists” (Conant). Contemporary examples of this challenge include genome editing with CRISPR in biotechnology and generative artificial intelligence (AI) with large language models in computer science. The expectation of a dramatic reduction in road traffic accidents after the transition to AVs is well-founded. However, the idea that all traffic accidents will be a phenomenon of the past is utopian. My students and I assume that these accidents will decline, but still happen, and that societal scrutiny of robot car fatalities will increase, especially in some edge cases, where the automotive AI will compute alternative outcomes and make an unforced decision based on different (non-universal) ethical theories, such as utilitarianism or Kantianism.
  Nov 21	No Colloquium	Thanksgiving Week.
  Nov 28	No Colloquium	--
  Dec 5	Keshav Dani Okinawa Inst. of Sci. & Tech. Graduate University	Imaging photoinduced phenomenon in real and momentum space Photoemission spectroscopy techniques – wherein one photoemits an electron from a material using a high-energy photon to study its properties – have provided unparalleled insight into materials and condensed matter systems over the past several decades. Among these, there are two particularly powerful and complementary techniques: angle-resolved photoemission spectroscopy (ARPES), which resolves the momentum of the photoemitted electron in the material; and photoemission electron microscopy (PEEM), which resolves its spatial coordinate. Recently, the merger of these techniques into multi-dimensional platforms of photoemission spectroscopy, along with access to the temporal dimension by further incorporating ultrafast spectroscopy techniques, have enabled powerful visuals of the dynamics of photoexcited systems in real and momentum space. In the first part of the talk, I will discuss some recent work in my lab in visualizing photoexcited carriers in space, time and energy [1, 2]. Applying these techniques to state-of-the-art perovskite photovoltaic films, we will image the performance limiting nanoscale defect clusters in these next-gen solar materials [3], and understand their role in charge trapping [4, 5]. In the second part of the talk, we will turn our attention to imaging momentum space in photoexcited 2D semiconductors and heterostructures [6]. Thereby, we will directly image the distribution of an electron around a hole in an exciton [7] – a hydrogen-like state that forms when a semiconductor absorbs light; visualize dark excitonic states that have largely remained hidden to optical experiments [8], and observe the structure of a moiré trapped interlayer exciton [9]. [1] Nature Nanotech.12, 36 (2017) [2] Science Advances4, eaat9722 (2018) [3] Nature580, 360 (2020) [4] Energy & Environ. Science14, 6320 (2021) [5] Nature 607, 294 (2022) [6] Advanced Materials DOI 10.1002/adma.202204120 (2022) [7] Science Advances7, eabg0192 (2021) [8] Science370, 1199 (2020) [9] Nature603, 247 (2022)

• Spring 2023 Colloquia

  Spring 2023 Colloquia

  Date	Speaker	Title & Abstract
  Feb 7	Alyson Brooks Rutgers	What is the Matter with Dwarf Galaxies? The large-scale structure of our Universe is well described by a model in which matter is predominantly Cold Dark Matter (CDM). While CDM was initially thought to have trouble reproducing the small scales of our Universe (dwarf galaxies and the central regions of galaxies like the Milky Way), it has generally become accepted in the last decade that a proper treatment of the gas and stars (baryonic matter) can alleviate those tensions. However, the models of energetic "feedback" from stars that have solved some of the tensions in CDM are now running into trouble solving new problems, specifically the "diversity of rotation curves" problem. In this talk, I will highlight the successes and troubles of current baryonic models, and discuss whether self-interacting dark matter (SIDM) might be a better model to explain observations.
  Feb 14	Phil Phillips UIUC	Beyond BCS: An Exact Model for Superconductivity and Mottness The Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity described all superconductors until the 1986 discovery of the high-temperature counterpart in the cuprate ceramic materials. This discovery has challenged conventional wisdom as these materials are well known to violate the basic tenets of the Landau Fermi liquid theory of metals, crucial to the BCS solution. Precisely what should be used to replace Landau's theory remains an open question. The natural question arises: What is the simplest model for a non-Fermi liquid that yields tractable results. Our work builds[1] on an overlooked symmetry that is broken in the normal state of generic models for the cuprates and hence serves as a fixed point. A surprise is that this fixed point also exhibits Cooper's instability[2,3]. However, the resultant superconducting state differs drastically[3] from that of the standard BCS theory. For example the famous Hebel-Slichter peak is absent and the elementary excitations are no longer linear combinations of particles and holes but rather are superpositions of composite excitations. Our analysis here points a way forward in computing the superconducting properties of strongly correlated electron matter. [1] E. Huang, G. La Nave, P. Phillips, Nat. Phys., 18, pages 511–516 (2022). [2] PWP, L. Yeo, E. Huang, Nature Physics, 16, 1175-1180 (2020). [3] J. Zhao, L. Yeo, E. Huang, PWP, PRB, Phys. Rev. B 105, 184509 (2022).
  Feb 21	Zoe Yan Princeton	Microscopy of quantum correlations in an ultracold molecular gas Ultracold molecules are a promising platform for quantum simulation of spin physics due to their long-range interactions and large set of internal states. To understand the complex many-body states that emerge in these systems, both in and out of equilibrium, new experimental techniques are needed to probe molecule correlations in the strongly interacting regime. We study the site-resolved dynamics of spin correlations in a gas of ultracold NaRb molecules in a 2D optical lattice. The molecules realize a quantum XY model with long-range interactions. Using a site-resolved Ramsey interferometric technique, we detect oscillations in nearest- and next-nearest-neighbor correlations due to spin interactions. Furthermore, we apply a periodic external microwave field to engineer XXZ spin Hamiltonians with tunable anisotropies. The correlations are measured by dissociating the molecules and detecting the corresponding Rb atoms with single-site resolution using a quantum gas microscope. The techniques presented here open new doors for probing quantum correlations in complex many-body systems of ultracold molecules.
  Feb 28	Feliciano Giustino UT Austin	The polaron turns ninety In 1933, Lev Landau wrote a 500-word article analyzing what might happen when an electron travels through a crystal lattice. That deceivingly simple paper marked the birthdate of the concept of polarons. Ninety years on, new experiments and new high-performance computing methods are helping us to shed light on these ubiquitous yet elusive entities. Polarons are emergent quasiparticles that arise from the interaction between fermions and bosons. In crystals, polarons form when an electron becomes dressed by a cloud of virtual phonons in the form of a distortion of the atomic lattice. In the presence of weak electron-phonon interactions, polarons behave like conventional Bloch waves, only with slightly heavier masses. In the presence of strong interactions, on the other hand, polarons become localized wavepackets and profoundly alter the transport, electrical, and optical properties of the host material. In applications, polarons are important in solar photovoltaics, photocatalysis, touchscreens, organic displays, and even neuromorphic computing. In this talk I will introduce the notion of polarons starting from elementary models that capture their essential features. Then I will describe recent explorations of polaron physics from the point of view of first-principles atomic-scale calculations, ranging from density-functional theory to many-body field-theoretic methods. Since we are at Stony Brook, I will also show that the theory of polarons is closely related to the pioneering work by Prof. Allen on the temperature dependence of electronic band structures in crystals. These and many other recent advances in the field raise the hope that it will soon be possible to engineer advanced materials with tailored polaronic properties. Feliciano Giustino is Professor of Physics at the University of Texas, Austin, and holds the W. A. "Tex" Moncrief, Jr. Chair in Quantum Materials Engineering. He earned his Ph.D. in Physics at the Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland, and held a post-doctoral appointment at the University of California, Berkeley. Prior to joining the University of Texas, he spent over a decade at the University of Oxford as Professor of Materials Science, and one year at Cornell University as the Mary Shepard B. Upson Visiting Professor in Engineering. He is the recipient of a Leverhulme Research Leadership Award, a Fellow of the American Physical Society, and a Clarivate Analytics Highly Cited Researcher. He serves on the Executive Editorial Board of JPhys Materials. He specializes in electronic structure theory, high-performance computing, and the quantum design of advanced materials at the atomic scale. He is author of 160+ scientific publications and one book on density-functional theory published by Oxford University Press. He initiated the open-source software project EPW, which is regularly used by research groups around the world.
  Mar 7	--	No colloquium.
  Mar 14	--	Spring Break. No colloquium.
  Mar 21	Monica Plisch Director of Programs, American Physical Society	Strengthening the Future of Physics by through Teacher Preparation The enterprise of physics depends on a strong K-12 educational system to prepare and inspire the next generation of physicists. One major challenge is the severe shortage of highly qualified high school physics teachers: each year in the US, colleges and universities only graduate about one-third of the new teachers needed to replace those who retire or leave the profession. As a result, many high school students do not have the opportunity to learn physics from a qualified teacher. In response to this challenge, the American Physical Society (APS) and the American Association of Physics Teachers (AAPT) launched the Physics Teacher Education Coalition (PhysTEC). PhysTEC catalyzes and supports efforts within physics departments across the US to engage in recruiting and educating future K-12 physics teachers. The project has developed several successful models for addressing the physics teacher shortage. Stony Brook University is the lead institution for a PhysTEC Regional Network, a new approach that connects nearby institutions and stakeholders to address shared goals and work collectively to educate greater numbers of highly qualified physics teachers. In this colloquium, I will present our findings and how these successes are shaping the future of PhysTEC.
  Mar 28	Tanya Zelevinsky Columbia University	Ultracold-Molecule Clocks Ultracold atom technologies have transformed our ability to perform high-precision spectroscopy and apply it to time and frequency metrology. Many of the highest-performing atomic clocks are based on laser-cooled atoms trapped in optical interference patterns. These clocks can be applied to fundamental questions, for example to improve our understanding of gravity and general relativity. In this talk, I will discuss using optically trapped ultracold diatomic molecules, rather than atoms, as a reference for clocks. Molecules have more internal quantum states and therefore are relatively challenging to control. On the other hand, their vibrational modes offer a large number of prospective clock transitions, and can help us probe alternative aspects of new physical interactions. I will discuss the current precision limit of molecular metrology and possible paths forward.
  Apr 4	Elena D'Onghia University of Wisconsin	When do stellar disks form stellar bars? James Webb Space Telescope (JWST) has unveiled galaxies two billion years after the Big Bang, showing a bar, an elongated stellar structure at the galaxy center. How these structures could develop so quickly in the early disk galaxies, remain a mystery. Using high-resolution N-body simulations, I have investigated the stability of stellar disks to the formation of bars. To date, no convincing global criterion regulates the formation of bars in disk galaxies. Here I revisit the problem and depart from traditional approaches. I assume the disk exists in the potential of an external force field and its self-gravity. The simulations show that two global dimensionless disk parameters appear to control the instability and the bar formation. One is related to the order and disordered stellar motions, and the other is the ratio of the disk self-gravitation to the total potential. The two parameters define a plane of disk stability to the bar formation. Unlike the Toomre Q parameter, which regulates the stability of the disk locally, they are global in that they describe the global survivability of the structure. The two parameters are crucial in stabilizing a broad class of disks to bar formation at all scales. The criterion should apply to small to large scales, from nuclear stellar disks around black holes to the galaxy disks in the early universe, and provide a theoretical framework to interpret the observations made by JWST.
  Apr 11	Nathan Jackson, Evan Trommer, Yu Wang, Tobias Weiss Stony Brook University	Inaugural Undergraduate Colloquium The inaugural Undergraduate Research Day held March 31 was a smashing success. The faculty research presentations, faculty panel discussion, and undergrad research poster presentations were all filled with positive engagement, enthusiasm, and energy, along with great scientific content. There were a total of 17 excellent poster presentations and the faculty judges selected the following four presentations to be orally presented, each with a length of 10 minutes. Nathan Jackson, Probing dark matter by bombarding tantalum with low-energy electrons: protocol for the DarkLight experiment Evan Trommer, Probing the Electromagnetic Field Structure in Plasma Wakefields Using Relativistic Electrons Yu Wang, Hyperradial Distribution of Few-Body Problem Tobias Weiss, Generating Ferromagnetic Lattices Faster with Machine Learning
  Apr 18	Chris Ashall Virginia Tech	The Mid Infrared Revolution: Supernovae with the James Webb Space Telescope The recent Launch of the James Webb Space Telescope has transformed our understanding of the Universe. In this talk I will present some the most exciting JWST results from the past year including highlights from the launch and first light images. I then turn to my two JWST Cycle 1 programs. I present the first ever observations of supernovae (SNe) with JWST. These programs use JWST data to reveal previously unknown physics about SNe explosions. As cauldrons of nucleosynthesis, SNe provide the interstellar medium with heavy elements and are key to its isotopic composition. However, we do not yet understand the details of how they explode, what their progenitors are, or how they contribute to the dust budget of the universe. For Type Ia Supernovae (SNe Ia), which come from the demise of white dwarfs (WD), I will show how JWST observations can accurately measure the mass of the primary WD, as well as chemical asphericities within the explosion. For Core Collapse SN (CC SN), which come from the death of massive stars, I will demonstrate how JWST observations can be used to determine the dust produced in these cosmic explosions. Finally, I will discuss what future JWST observations will reveal about SNe. Overall, JWST is a truly exciting time for astronomy and is beginning to revolutionize SN physics.
  Apr 25	Xu Du Stony Brook University	Building a Meta World on Graphene Condensed matter physics is largely a study of materials. Besides the bottom-up approach of material synthesis and characterizations, the top-down approach of nano-patterning offers an alternative way to build artificial quantum systems and materials on simple 2d electron gas, with great controllability, flexibility, and versatility. I will give an overview of some of the recent developments from my lab on such an approach. A quantum Hall antidot, for example, behaves like an artificial atom which localizes quantum Hall quasiparticles. And coupling several quantum Hall antidots together forms an artificial molecule which can be used to study the quantum exchange statistics of the quantum Hall quasiparticles. And towards realizing artificial 2d crystals, our recent work on creating electrically tunable superlattices on Bernal-stacked bilayer graphene demonstrated modification of its intrinsic electronic properties and formation of a stack of flat energy bands which result in correlated insulator behavior. These developments open the opportunities for studying the exotic quasiparticles and strongly correlated electrons in 2d systems.
  May 2	Matthew Dawber Stony Brook University	Graduate colloquium.

• Fall 2022 Colloquia

  Date	Speaker	Title & Abstract
  Sep 6	Barry Barish Professor of Physics, Emeritus, Caltech Distinguished Professor of Physics, UC Riverside Nobel Laureate, 2017	Inaugural C.N. Yang Colloquium Probing the Universe with Gravitational Waves The discovery of gravitational waves, predicted by Einstein in 1916, is enabling both important tests of the theory of general relativity, and represents the birth of a new astronomy. Modern astronomy, using all types of electromagnetic radiation, has giving us an amazing understanding of the complexities of the universe, and how it has evolved. Now, gravitational waves and neutrinos are beginning to provide the opportunity to pursue some of the same astrophysical phenomena in very different ways, as well as to observe phenomena that cannot be studied with electromagnetic radiation. The detection of gravitational waves and the emergence and prospects for this exciting new science will be explored.
  Sep 13	Chang Kee Jung Stony Brook University	Chair's Colloquium
  Sep 20	--	No colloquium.
  Sep 27	--	No colloquium.
  Oct 4	Mariangela Lisanti Princeton	Galactic Probes of Fundamental Dark Matter Physics The hypothesis of Cold Dark Matter (CDM) has been spectacularly confirmed on the largest scales of the Universe and must now be stress-tested on galactic scales. Many well-motivated and generic alternatives to CDM can leave spectacular signatures on precisely these scales, affecting the evolution of galaxies as well as their population statistics. Excitingly, over the course of the next decade, a flood of astrophysical data will open the possibility of searching for these distinctive imprints and shedding light on key questions about dark matter. In interpreting such results, systematic studies using both semi-analytic codes and numerical simulations will play a critical role in robustly disambiguating dark matter signals from other standard baryonic processes. As a concrete example in this talk, I will describe the consequences for galaxy formation when new forces mediate interactions between dark matter particles, highlighting key observables for future studies.
  Oct 11		Fall Break. No colloquium.
  Oct 18	Peter Denton Brookhaven National Laboratory	Knowns and Unknowns in Neutrinos In particle physics there exist two regions: the Standard Model which is fairly complete and the new physics sector which is completely unknown. Inbetween and overlapping with both of these is neutrino physics. Neutrinos exist within the Standard Model but are not explained by it due to the discovery of neutrino oscillations. In this colloquium I will discuss where we stand with neutrino oscillations, where we might go with them, and how we might learn about the nature of neutrinos.
  Oct 25	Talat Rahman University of Central Florida	The Importance of Being Imperfect: Defected 2D Materials for a Sustainable Future In the pursuit of a sustainable future, the last decade has seen a concerted effort in accelerating the discovery of materials for energy needs, thanks to a large extent to the Materials Genome Initiative. In this talk I will focus on few 2-dimensional materials which have captured our imagination. As with graphene, another common lubricant, molybdenum disulphide (MoS2) shows remarkable optical properties when peeled off as single sheet. I will show how defects and dopants in single-layer MoS2 transform its electronic structure so that it turns into a catalyst for CO hydrogenation. Even more interesting is the case of another 2D material, good old hexagonal boron nitride (h-BN), an avowed insulator. Defects, however, can transform it into a material that, on the one hand, captures and converts CO2 to value added products and, on the other, functions as a single photon emitter akin to NV centers in diamond. With a focus on electronic structural modulations of the local environment, I will draw comparisons with experimental observations made in collaborative work.
  Nov 1	Robert Crease Stony Brook University	The Leak: The Life and Untimely Death of Brookhaven's High Flux Beam Reactor In 1997, a small leak of tritium-containing water from the spent fuel pool of the HFBR (High Flux Beam Reactor) triggered a media and political firestorm that resulted in the reactor's shutdown and calls to close the laboratory. A quarter-century later, the episode embodies the dynamics of controversies in which fears and political agendas disrupt serious discussion and research of vital issues. Robert P. Crease is a Professor in and Chair of the Stony Brook Department of Philosophy. For 22 years he has written a column for Physics World, "Critical Point," on the historical and philosophical dimensions of science. He won the 2021 Institute of Physics Kelvin Medal for "describing key humanities concepts for scientists, and explaining the significance of key scientific ideas for humanists." His most recent book (with Peter Bond) is The Leak: Politics, Activism, and Loss of Trust at Brookhaven National lLaboratory (MIT Press).
  Nov 8		Election Day. No colloquium.
  Nov 15	Jen Cano Stony Brook University	A New Era of Topological Materials Topology plays an important role in our understanding of quantum matter. The topological classification of electronic bands gives rise to “topological insulators.” These phases are not only mathematically elegant, but also exhibit unusual physical properties sought after for next generation quantum electronics. While the past decade marked the search for topological materials, the goal of the next decade will be to detect, engineer, and manipulate their properties. I will describe theoretical advances that have broadened the classification of topological phases, giving rise to new probes and materials. Finally, I will introduce “topological twistronics” as a novel tuning knob to manipulate these exotic phases of matter.
  Nov 22		Thanksgiving Break. No colloquium.
  Nov 29	Giacinto Piacquadio Stony Brook University	Beauty (quarks) and the Higgs as Window into New Physics at the LHC Ten years ago, the discovery of the Higgs boson based on proton-proton collisions at the Large Hadron Collider provided experimental confirmation of the mechanism that gives elementary particles their mass. Today the Run-2 and Run-3 datasets, with their record-breaking proton-proton intensity and the highest collision energies ever produced by mankind, are enabling ATLAS and CMS experiments to perform measurements of the newly discovered particle with unprecedented precision, providing stringent tests for an increasing class of new physics models. After giving a general overview of the status of the field, I will explain why beauty quarks, the particles to which the Higgs boson decays more abundantly, represent such a challenging yet essential tool to study the Higgs boson, and how the deployment of machine learning tools is helping us extend the discovery reach to previously unexplored scenarios. Finally, I will discuss the prospects for Higgs boson measurements during the High-Luminosity phase of the LHC.
  Dec 6	Valeria Molinero University of Utah	Molecular Recognition of Ice by Proteins: From Ice Nucleation to Antifreeze Bacteria, insects and fish that thrive at subfreezing temperatures produce proteins that bind to ice and manage its formation and growth. Ice binding proteins include antifreeze proteins, that stop the formation of ice, and ice-nucleating proteins, that promote it. This presentation will discuss what makes proteins so outstanding at recognizing and binding ice, what distinguishes ice nucleating and antifreeze proteins, and how can we use that knowledge to engineer new molecules for a range of applications, from seeding clouds to induce precipitation to cryopreservation.

• Spring 2022 Colloquia

  Date	Speaker	Title & Abstract
  Feb 1	Navid Vafaei-Najafabadi Stony Brook University	Recruiting the 4th state of matter to miniaturize particle accelerators Particle accelerators have been an invaluable tool for scientific discovery and research. Future discoveries in high energy physics will require significantly more energetic particles than those currently produced. However, simply scaling the current machines to higher energies is a significant challenge because of their cost as well as the required space. A fundamental limitation that dictates the size of these machines is that the peak electric field used for accelerating particles must be below the damage threshold of the accelerating structures. Using a plasma, an ensemble of ionized atoms also known as the fourth state of matter, this limitation can be circumvented. In particular, high amplitude waves can be generated in a plasma using a high-power laser or a particle beam. The resulting structures have been shown to sustain accelerating fields that are hundreds of times higher than those currently generated in particle accelerators. In this talk, I will discuss how plasma waves are particularly well suited for accelerating electrons, the status of the state-of-art research, as well as the challenges that need to be overcome for plasma-based accelerators to form the foundation of next generation of high-energy particle beams.
  Feb 8	Wendy Freedman University of Chicago	This colloquium will be fully virtual. Increasing Accuracy in Measurements of the Hubble Constant: Is There Evidence for New Physics? An important and unresolved question in cosmology today is whether there is new physics that is missing from our current standard Lambda Cold Dark Matter (LCDM) model. Recent measurements of the Hubble constant, Ho -- based on Cepheids and Type Ia supernovae (SNe) -- are discrepant at the 4-5-sigma level with values of Ho inferred from measurements of fluctuations in the cosmic microwave background (CMB). The latter assumes LCDM, and the former assumes that systematics have been fully accounted for. If real, the current discrepancy could be signaling a new physical property of the universe. I will present new results based on an independent calibration of SNe Ho based on measurements of the Tip of the Red Giant Branch (TRGB). The TRGB marks the luminosity at which the core helium flash in low-mass stars occurs, and provides an excellent standard candle. Moreover, the TRGB method is less susceptible to extinction by dust, to metallicity effects, and to crowding/blending effects than Cepheid variable stars.   I will  address the current uncertainties in both the TRGB and Cepheid distance scales, the promise of upcoming James Webb Space Telescope data, as well as discuss the current tension in Ho and whether there is need for additional physics beyond the standard LCDM model.
  Feb 15	Jin Koda Stony Brook University	Increasing Accuracy in Measurements of the Hubble Constant: Is There Evidence for New Physics? Molecular gas and molecular clouds host virtually all star formation in the local Universe, and therefore their formation and evolution are the first step leading to star formation and galaxy evolution. In this talk, I will argue for long life and evolutional timescales of molecular gas and clouds (~>100Myr), as opposed to the recently-(again)-suggested short timescales (10-30Myr), by looking at their evolution through galactic rotation, i.e., how they form and evolve through spiral arms and inter-arm regions, in the Milky Way and in nearby galaxies. Although the popular spiral density-wave theory predicts a rapid phase transition from atomic to molecular and then to atomic phases through spiral arm passages, the observed fraction of molecular gas over atomic gas remains high even in the inter-arm regions in MW-like spiral galaxies. Hence, the molecular gas and clouds are not destroyed much toward the inter-arm regions. Recent ALMA data show diverse molecular structures in the inter-arm regions of nearby galaxies, many of which contain large masses. Their formation requires very long timescales (~100Myr) just to assemble the masses. If they are destroyed quickly in the short timescales, their formation would not catch up with the destruction; the galaxies should have much more atomic gas than the observed. The long life and evolutional timescale of molecular gas impacts the picture of star formation - the star formation has to be triggered in the long-existing molecular structures, rather than starting at an onset of gravitational collapse from diffuse atomic gas to dense molecular clouds. Until August 14, 2022, a recording of this colloquium may be accessed here, using the following passcode: 91.?S1YD
  Feb 22	Murray Holland University of Colorado Boulder	Extreme sensing, clocks, and squeezing atoms and molecules with light I will describe recent ideas for lowering the temperature of ensembles of ultracold atoms and molecules into the extreme quantum regime, for using interactions to entangle atoms and molecules into non-classical quantum states, and for using these non-classical states to realize quantum advantages for metrology, clocks, and matter-wave interferometry. One such topic is a new experimentally demonstrated idea for laser cooling by Sawtooth Wave Adiabatic Passage (SWAP). This is mostly relevant to atoms and molecules that possess narrow linewidth transitions, such as the ultranarrow clock transitions, and promises to be an important extension to the toolbox of AMO physics for laser cooling and trapping. We are exploring ways to use optical cavities and cavity-mediated interactions to entangle atoms so that we may improve optical clock performance, make repeated quantum measurements beyond the standard quantum limit, and continuously track squeezed quantum phases. These approaches take full advantage of the powerful combination of the extreme optical coherence that is possible using atomic clocks, with the rich possibilities offered by many-body physics that arises when the atoms interact strongly. Atomic clocks have already progressed to the point that understanding how to take advantage of quantum effects will be crucial in order to progress to the next generation of devices. Until August 21, 2022, a recording of this colloquium may be accessed here, using the following passcode: =3V&hEVn
  Mar 1		No colloquium.
  Mar 8	Laura Cadonati Georgia Institute of Technology	Exploring the cosmic graveyard with gravitational waves A new era in astrophysics has begun with the 2015 discovery of gravitational waves from the collision of two black holes in data from the Laser Interferometer Gravitational-wave Observatory (LIGO). The additional 2017 LIGO-Virgo detection of gravitational waves from the collision of two neutron stars in coincidence with a gamma ray burst and a kilonova, elevated multi-messenger astrophysics from concept to tool for discovery and exploration. Many more gravitational wave signals have been observed since then from collisions of compact binary coalescence, and gravitational waves are a new, important probe for understanding the universe, with a rich science potential ranging from astronomy to cosmology to nuclear physics. This talk will present a selection of the  latest results from LIGO and Virgo, with their GWTC-3 gravitational wave transient catalog, and an outlook for the next decade.
  Mar 22	Alexandra Gade Michigan State University	This colloquium will be fully virtual. The science of FRIB: From the nuclear many-body challenge to the origin of the elements in the Universe There are approximately 300 stable and 3,000 known unstable (rare) isotopes. Estimates are that over 7,000 different isotopes are bound by the nuclear force. It is now recognized that the properties of many yet undiscovered rare isotopes hold the key to understanding how to develop a comprehensive and predictive model of atomic nuclei, to accurately model a variety of astrophysical environments, and to understand the origin and history of elements in the Universe. Some of these isotopes also offer the possibility to study nature's underlying fundamental symmetries and to explore new societal applications of rare isotopes. This presentation will give a glimpse of the opportunities that arise once the Facility for Rare Isotope Beams (FRIB) comes online at Michigan State University in a few weeks. Until September 18, 2022, a recording of this colloquium may be accessed here, using the following passcode: &n5*qKQK
  Mar 29	Dmitry Tsybychev Stony Brook University	Experimental studies of the electroweak symmetry breaking at CERN Large Hadron Collider Understanding of electroweak symmetry breaking mechanism is one of the highest priority problems facing the field of high-energy physics and most importantly whether such breaking occurs solely through the weak interactions. The divergence of electroweak interactions in the Standard Model of particle physics, in particular, scattering of longitudinally polarized of heavy gauge bosons, at the TeV scale is solved by introduction of a Higgs boson. We will present studies of the electroweak symmetry breaking at ATLAS experiment at the Large Hadron Collider (LHC), operating at center-of-mass energies of 7-14 TeV, the highest collision energy in the world. Until September 25, 2022, a recording of this colloquium may be accessed here, using the following passcode: d?n9qHse
  Apr 5	Heather Gray Berkeley	Computing Challenges for Future Colliders — could quantum computing play a role? High-energy physics is facing a daunting computing challenge with the large and complex datasets expected from the HL-LHC in the next decade and future colliders to follow the LHC. The landscape of computing has been evolving rapidly and field of quantum computing in particular has been making dramatic progress in recent years. I will outline the challenges facing high-energy physics, provide a brief introduction to quantum computing focusing on recent progress and discuss recent work that may lead to solutions for high-energy physics.
  Apr 12	Dave Kawalll University of Massachusetts	An Anomaly in an Anomaly? First Results from the Fermilab Muon g-2 Experiment The Fermilab muon g-2 experiment recently released its first measurement of the magnetic behavior of the muon. Muons are like electrons, but heavier and short-lived. Their magnetic properties can be predicted with impressive, sub-ppm precision through the techniques of quantum field theory. An interesting feature is that an accurate prediction requires the addition of quantum corrections that arise due the interactions of the muon with all the other fundamental particles of nature such as electrons, photons, quarks, etc. Comparison of experimental results with theoretical predictions then serves as a powerful test of the completeness of the Standard Model of nature, and the long-standing discrepancy we observe might indicate the need for new physics. The concepts behind the Fermilab experiment and the many challenges it faces will be presented, along with the comparison with theory and future prospects. Until October 9, 2022, a recording of this colloquium may be accessed here, using the following passcode: CyYyXU$0
  Apr 19	Mark Palmer Brookhaven National Laboratory	An Energy Frontier Muon Collider: Progress Towards a Machine to Drive Particle Physics Discovery Muon colliders offer a unique path to multi-TeV, high-luminosity lepton collisions. Muon collisions with a center-of-mass energy of 10 TeV or above would offer significant discovery potential where the constituent collision energies exceed those of the LHC program by an order of magnitude. Significant progress on the fundamental R&D and design concepts for such a machine has led to a new international effort to assemble a conceptual design within the next few years. This effort will assess the viability of such a machine as a successor to the LHC program. The remaining challenges and the R&D required to deliver a complete machine description will be described. Until October 16, 2022, a recording of this colloquium may be accessed here, using the following passcode: b*&J29Z8
  Apr 26	John Wilkerson University of North Carolina	This colloquium will be fully virtual. Probing the elusive nature of neutrinos Neutrinos, enigmatic fundamental particles, were long assumed to be massless until a series of revolutionary experiments over the past two decades revealed that they actually exhibit complex behavior and must possess non-zero mass. From these and other recent measurements we know that neutrinos have minuscule masses, at least 500,000 times lighter than the electron. Yet we still do not know the neutrino’s actual mass nor why it is so light? Nor do we understand their fundamental nature, are they Dirac or Majorana particles? If neutrinos are their own antiparticles, Majorana neutrinos, then this would provide an explanation for their elusive lightness while at the same time offering a potential explanation of the universe’s observed matter - antimatter asymmetry. This talk will briefly review our current understanding of neutrinos, their role in cosmology, astrophysics, and fundamental interactions, and then address the questions of both how one “weighs” a neutrino and how to determine its Dirac or Majorana nature. The techniques and latest results from cosmology, direct kinematical methods, and double beta decay will be presented. Until October 23, 2022, a recording of this colloquium may be accessed here, using the following passcode: H4Uq.v$1
  May 3	Matthew Dawber Stony Brook University	Graduate Colloquium

• Fall 2021 Colloquia

  Date	Speaker	Title & Abstract
  Aug 31	Matthew Dawber Stony Brook University	Building better functional materials with advanced deposition and x-ray diffraction If the oft-quoted maxim in materials design is that “the whole is more than the sum of the parts”, it is also true that “the devil is in the details”.  In the case of ferroelectric oxides, this is especially true. Our work in building artificially layered heterostructure of these materials has shown that their key functional properties, including the nanoscale arrangement of electrical polarization and their ability to act as photocatalysts to generate hydrogen fuel, are determined by events that occur during their fabrication. They also depend strongly on tiny details such as the precise arrangement of atoms on their surfaces. Hence we will add to our list of handily appropriate sayings, “the journey is as important as the destination”.  Historically, the approach to material fabrication has largely been like taking a red-eye with your eyeshades on, you know where you started and where you land, but have very little idea about what happened in between. (It’s also pretty tedious and uncomfortable).  Through the use of synchrotron x-ray diffraction performed in-situ during growth and other dynamic processes we have begun to peel off the eyeshades, learning a great deal about the processes and also developing insight into how we can influence the processes at key points to greatly enhance the final properties of our materials. It’s a bit like being awake when the meal cart goes by, i.e., very much to your advantage!
  Sept 7	Chang Kee Jung Stony Brook University	Chairs Colloquium
  Sept 14	Gregory Falkovich Weizmann Institute	Physical Nature of Information How much can we do and say about something we do not know? Trying to answer this question quantitatively brought us thermodynamics, statistical mechanics and information theory. I shall present a brief history of these developments, emphasizing the analogies in the limits imposed by uncertainty on engines, measurements, communications and computations. The review is panoramic aiming to show that the people working on quantum computers and the entropy of black holes use the same tools as those designing self-driving cars and market strategies, studying molecular biology, animal behavior and human languages, and figuring out how the brain works. I’ll finish with some recent applications to turbulence as an ultimate far-from-equilibrium state with the lowest entropy.
  October 19	Xiaoxing Xi Temple University	Crackdown on Academic Collaboration with China Harms American Science Academic collaboration with China was once encouraged by the US government and universities. As tension between the two countries rises rapidly, those who did, especially scientists of Chinese descent, are under heightened scrutiny by the federal government. Law enforcement officials consider collaborating with Chinese colleagues “by definition conveying sensitive information to the Chinese.” In 2015, I became a casualty of this campaign despite being innocent. “China Initiative” established by the Justice Department in 2018 has resulted in numerous prosecutions of university professors for alleged failure to disclose China ties. In this talk, I argue that academic decoupling is not in America’s interest. It is a tall order to convince the public and policy makers of this fact, but the scientific community must try lest the American leadership in science and technology will be irreparably damaged.
  November 2	Angela Kelly Stony Brook University	Access and Equity in the Physics Education Pipeline Science, technology, engineering, and mathematics (STEM) careers have traditionally served as mechanisms for socioeconomic advancement in the U.S., yet participation in academic coursework that prepares students for the STEM workforce has not been equitable. Recent calls for reform in physics education have highlighted persistent disparities in access and equity for traditionally underrepresented populations in precollege and university settings. The Institute for STEM Education (I-STEM) at Stony Brook houses the Ph.D. Program in Science Education, where faculty and researchers examine important questions related to STEM educational outcomes. This colloquium will present recent research exploring three main segments of the physics education pipeline: (1) physics educational opportunities, participation, and teacher quality in high school settings; (2) science academic gatekeeping in community colleges; and (3) undergraduate experiences in physics, particularly remote laboratory classes. Findings utilizing a variety of research methodologies will be presented, along with implications for policy and practice in physics education.
  November 9	Sergey Syritsyn Stony Brook University	A more perfect Universe: the role of lattice QCD in constraining fundamental symmetry violations Violations of fundamental symmetries, in particular CP(charge*parity) and baryon number conservation, are immensely important to understanding the origin of matter in the Universe. Evidence for such violations, such as proton decay, neutron-antineutron oscillation, and the neutron electric dipole moment, have not yet been observed despite decades of dedicated experiments. In these searches, the common "probes" are protons and neutrons. Precise knowledge of their structure in terms of their elementary constituents, quarks and gluons, is crucial to connecting experimental bounds to theories incorporating symmetry violations. In my talk, I will review the role, the methods, and the status of Quantum Chromodynamics calculations on a lattice that connects quark-gluon interactions and nucleon structure.
  November 16	Anja von der Linden Stony Brook University	Cosmology with Galaxy Clusters The observed number of galaxy clusters provides a sensitive probe of the structure of the Universe, including dark energy, by measuring the evolution of the halo mass function. However, already current cluster surveys are systematically limited by uncertainties in the relation between cluster mass and observables (e.g. number of galaxies, X-ray luminosity, or the imprint on the Cosmic Microwave Background). I will discuss the challenges in determining mass-observable relations, and how the combination of weak gravitational lensing and X-ray observations can address these. I will review current cluster cosmology results, including those from the "Weighing the Giants" project which placed some of the tightest single-probe constraints on dark energy to date. I will comment on how cluster triaxiality and orientation bias can alleviate the surprisingly low matter density inferred from clusters in the Dark Energy Survey. I will conclude with an outlook towards cluster cosmology with future sky surveys, in particular the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST).
  November 30	Xijie Wang SLAC	Watch water molecules dancing with MeV electrons   Water is one of the most important, yet least understood, liquids in nature. Many strange properties of liquid water, such the highest density at 39 degrees Fahrenheit and high surface tension, originate from its well-connected hydrogen bond network. A complete unveiling of the intermolecular dynamics of water requires direct time- and structure-resolved measurements. It is a challenge to  use X-ray or  neutron scattering to study water’s hydrogen bond structure dynamics due to the lacking in scattering sensitivity (X-ray) or time resolution (neutron).  Recent developments in megaelectronvolt electron ultrafast electron diffraction (MeV-UED) [1-3] made it possible, for the first time, watching water molecule interacts with its neighbors [4] and formation of the short-lived hydroxyl-hydronium pair of the ionized water molecule [5].  Our experiment directly observed the quantum mechanical nature of how the hydrogen atoms are spaced out, and this quantum effect could be the missing link in theoretical models describing strange properties of water. I will also discuss development of MeV-UED - a new paradigm in ultrafast electron scattering.