Archived Colloquium Schedules
| Date | Speaker | Title & Abstract |
| Aug 26 |
Physics and Astronomy Department Chair |
|
| Sep 2 |
Joanna Kiryluk Stony Brook University |
IceCube is a one cubic kilometer neutrino observatory, completed in 2010 at the South Pole in Antarctica. In 2012, IceCube detected the first Peta electron-volt neutrino events and measured an unexpectedly large diffuse astrophysical neutrino flux. Since then, IceCube has characterized this flux with different event selection methods and event topologies, cascades and tracks induced by neutrinos of different flavors in the TeV-PeV energy range. The results are well described by a single power law with a spectral index of 2.5, softer than expected. Most recent precision data indicate a preference of a broken power law over a single power law. The origin(s) of the diffuse flux remains a largely open question. In 2017, an IceCube neutrino alert from the direction of the TXS 0506+056 galaxy triggered a multi-wavelength campaign of follow-up observations and identified this active galaxy as a cosmic ray accelerator and a source of both high energy neutrinos and gamma rays: a breakthrough in multi-messenger astronomy. Since then, IceCube found evidence that astrophysical neutrinos are also correlated with the NG1068 active galaxy and with the Galactic Plane. In this talk I will discuss IceCube results on the high energy neutrino diffuse flux
and searches on possible neutrino sources, results on the neutrino and anti-neutrino
scattering cross sections and implications for the structure of matter, as well as
detector future capabilities. |
| Sep 9 |
Alice Shapley University of California Los Angeles |
Understanding the formation and evolution of galaxies remains one of the great challenges
of modern cosmology. Key outstanding questions include: What are the physical processes
driving the formation of stars in galaxies? How do galaxies exchange material with
their intergalactic environments? How do the impressive variety of galactic structures
that we observe today assemble? How do supermassive black holes affect the evolution
of their host galaxies? We present a brief history of rest-optical spectroscopic probes
of the galaxy formation process at high redshift, ranging from early ground-based
attempts to the very latest results from the James Webb Space Telescope, which has
revolutionized our ability to learn about the most distant galaxies in the universe.
We focus in particular on questions related to the evolving enrichment and physical
conditions in the interstellar medium of star-forming galaxies in the early universe,
as these place critical constraints on the cycle of baryons through galaxies over
cosmic time. |
| Sep 16 |
University of Cambridge |
|
| Sep 23 |
Subir Sachdev Harvard University |
Complex many-electron entanglement can give rise to quantum states of matter that
lack any well-defined particle-like excitations. Recent theoretical advances in understanding
such states have provided significant insight into the diverse phases of the cuprate
materials, including high-temperature superconductivity. One such critical state is
a quantum spin liquid, in which the charge of some electrons is localized, while their
spins remain entangled in a scale-invariant manner; it offers a description of the
pseudogap phase. Another distinct critical state is associated with the collective
dynamics of electron charge, characteristic of the strange metal regime; its theoretical
description builds on concepts from the Sachdev-Ye-Kitaev (SYK) model. |
| Sep 30 |
-- |
|
| Oct 7 |
Ilsa Cooke University of British Columbia |
The interstellar medium is a fascinating place to study chemical reactions! This chemistry
is initiated by energetic particles and photons, forming ions and radicals that can
react in the gas phase and on the surface of dust grains, even at temperatures below
10 K. It is the ultimate physical chemistry laboratory! |
| Oct 14 |
-- |
|
| Oct 21 |
Adam Burrows Princeton University |
The theory of compact-object birth and supernovae is now entering a new and productive
phase of rapid insight into the mechanism and systematics of explosion. The panoramic
perspective provided by the recent access to tens of state-of-the-art 3D core-collapse
simulations taken to late times has revealed potential correlations between supernova
observables and physical trends with progenitors. A productive dialogue is slowly
emerging between theorists and observers that promises to transform the study of core-collapse
supernova explosions and to inaugurate a new era of physical characterization missing
from the past. Models now explode without artiface and theory is on the cusp of being
able to make predictions that seemed out of reach only a few years ago. We have discovered
correlations between explosion energy, neutron star gravitational birth masses, the
yields of the chemical elements, debris morphologies, pulsar kicks, and neutrino and
gravitational-wave emissions. However, while I contend the core-collapse supernova
problem is in broad outline and qualitatively now solved, there is much yet to do
in supernova theory before it can robustly and quantitatively explain the variety
of supernova observations. I will close with suggested paths forward to achieve this
ultimate goal. |
| Oct 28 |
Peter van Nieuwenhuizen Stony Brook University |
How the Zeeman (1896) and Stark (1913) puzzles of spectra were solved by Goudsmit and Uhlenbeck’s concept of spin in 1925; and how spin found its natural place in the new quantum mechanics of Heisenberg (1925), Schrödinger (1926), Pauli (1927) and Dirac (1928). In 1896 Pieter Zeeman, assistant of Heike Kamerlingh Onnes and Hendrik Lorentz at
Leyden, discovered that spectral lines broadened if their sources were put in a magnetic
field. Lorentz had the year before discovered the Lorentz force, and used it to predict
that spectral lines should split into triplets or doublets. In 1897 Zeeman indeed
detected such triplets and doublets, and in 1902 he and Lorentz received the second
Nobel prize, but later it was found that the splittings were much more complicated.
Thirty years of utter confusion and despair followed, but in 1925 several discoveries
in rapid succession solved the problems of the “normal” and “anomalous” Zeeman effect:
Pauli’s exclusion principle (January), Heisenberg’s first paper on QM (July), Goudsmit
and Uhlenbeck’s spin (October), and the first paper on quantum field theory by Born,
Heisenberg and Jordan (November). |
| Nov 4 |
-- |
|
| Nov 11 |
Priya Natarajan Yale University |
A profound transformation is underway in our understanding of how the very first black
holes emerged and evolved in the infant Universe. These cosmic seeds—precursors to
today’s supermassive black holes—offer a unique window into the earliest stages of
structure formation. The combined power of JWST, Chandra, and Hubble is now revealing
the signatures of their birth, pointing to multiple seeding pathways. Among these,
the direct collapse of pristine gas clouds has gained striking new support, alongside the classical channel
of stellar remnants from the first generation of stars. In parallel, observations of the stochastic gravitational wave background and advances in cosmological simulations are beginning to connect these formative
epochs to the later assembly of galaxies and quasars. In this talk, I will chart our
evolving understanding of black hole origins—how light and heavy seeds form, grow,
and merge—and explore how forthcoming observations, including those from LISA, promise to discriminate among competing formation scenarios. I will conclude by
reflecting on the broader implications for cosmic evolution and on what these elusive
beginnings reveal about the invisible architecture of our Universe. |
| Nov 18 |
Xin Qian Brookhaven National Laboratory |
Neutrinos, central to both the Standard Model and our understanding of the universe,
revealed through oscillations the first particle-physics evidence of physics beyond
the minimal Standard Model. The rapid discovery of a non-zero θ₁₃ at Daya Bay opened
the path to addressing several fundamental questions in neutrino physics, while the
resolution of anomalies—historically crucial for breakthroughs—has deepened our understanding
and driven detector innovation. In this context, the development of liquid-argon time
projection chambers (LArTPCs), together with associated advances such as Wire-Cell
reconstruction in MicroBooNE, has pushed the frontier of experimental capability.
Looking ahead, DUNE, Hyper-Kamiokande, and JUNO, now under construction or beginning
data taking, promise transformative results: advancing the picture of neutrino mass
and mixing, serving as powerful neutrino observatories, and opening new avenues for
discoveries beyond the Standard Model—marking the beginning of an exciting new era
in precision neutrino physics and technology-driven exploration. |
| Nov 25 |
-- |
|
| Dec 2 |
Abhay Pasupathy Columbia University |
I will discuss the use of scan probe microscopy to gain microscopic insight into two separate quantum phenomena in solids. |
| Date | Speaker | Title & Abstract |
| Jan 28 |
Andre De Gouvea Northwestern University |
The discovery of nonzero neutrino masses shook the particle physics world at the turn
of the 21st century and remains the only concrete evidence that there is something
missing from the standard model of particle physics. I provide an overview of the
current status of neutrino physics, including some of the open questions and the many
avenues we are pursuing to answer them. |
| Feb 4 |
Raymond Blackwell Stony Brook University |
Strong interactions between electrons in a material give rise to a diverse set of
phenomena including superconductivity, density waves, and magnetism. One of the most
powerful techniques to study these correlated phenomena is Spectroscopic Imaging Scanning
Tunneling Microscopy (SI-STM), a real space probe capable of visualizing local electronic
information at sub-nanometer length scale. In this talk, I will discuss the insights
that SI-STM provides about the normal state in the recently discovered high Tc superconductor
La3Ni2O7. Additionally I will show evidence that ytterbium dopants drastically alter
the properties of graphene leading to spatial heterogeneity in the electronic structure
and the appearance of a charge density wave. |
| Feb 11 |
Jainendra Jain Penn State University |
The history of physics is replete with examples, referred to as paradigm shifts, where
a complex and apparently disconnected set of phenomena is unified by a more fundamental
principle. In this talk, I will show how the enormously rich and mysterious phenomenology
of 2D electrons in a magnetic field becomes obvious when viewed from the perspective
of a new kind of emergent particles called the composite fermions. In particular,
the composite fermions are seen to be the fundamental building blocks of the fractional
quantum Hall states, which are among the most stunning, the most consequential, and
the best understood strongly correlated states discovered in nature. I will mention
the latest developments, intriguing ideas for fault tolerant quantum computation,
new surprises, and open issues. The talk will be accessible to first year graduate
students. |
| Feb 18 |
Tom Hartman Cornell University |
Black holes in quantum gravity are complex objects, and the theory that governs them
provides a bridge between quantum field theory, statistical mechanics, and quantum
information theory. In this talk, I will describe some of these connections and give
a status report on the quantum theory of black holes. The emphasis is on the recent
discovery that spacetimes with higher topology --- multiple black holes, connected
through their interiors --- play an important role in the path integral of quantum
gravity. The talk will be an overview geared toward a general physics audience. |
| Feb 25 |
Dominik Schneble Stony Brook University |
Understanding and harnessing light-matter interactions in novel contexts is central
to the development of modern quantum technologies. One example is the emerging field
of waveguide quantum electrodynamics (wQED) which investigates the coherent coupling
between one or more quantum emitters and an engineered low-dimensional photonic bath.
While recent experiments have observed modified spontaneous emission, bound-state
mediated interactions, and superradiance, a clean access to the underlying mechanisms
often remains challenging. We approach wQED with an unconventional platform in which
artificial quantum emitters, realized with ultracold atoms in an optical lattice,
undergo spontaneous radiative decay by emitting single atoms, rather than single photons.
I will introduce the unique aspects of our matter-wave platform and present some recent
work on simulating radiative many-body effects at the boundary between atomic physics,
quantum optics and condensed-matter physics. |
| Mar 4 |
Alan Robock Rutgers University |
The world as we know it could end any day as a result of an accidental nuclear war between the United States and Russia. The fires produced by attacks on cities and industrial areas would generate smoke that would blow around the world, persist for years, and block out sunlight, producing a nuclear winter. Because temperatures would plunge below freezing, crops would die and massive starvation could kill most of humanity. Even a nuclear war between new nuclear states, such as India and Pakistan, could produce climate change unprecedented in recorded human history and massive disruptions to the world’s food supply. This talk will show climate and crop model simulations, as well as analogs, which
support this theory. It will also discuss policy changes that can immediately lessen
the chance of such scenarios happening and that can lead to the abolition of nuclear
weapons. The myth of nuclear deterrence has allowed nuclear weapons to persist for
too long. However, as a result of international negotiations pushed by civil society
led by the International Campaign to Abolish Nuclear Weapons (ICAN), and referencing
this work, the United Nations passed the Treaty on the Prohibition of Nuclear Weapons
(TPNW) on July 7, 2017. On December 10, 2017, ICAN accepted the Nobel Peace Prize
and the TPNW came into force on January 22, 2021, but the nine nuclear nations continue
to ignore the TPNW and the will of the rest of the world. An option for physicists
interested in getting involved is to join the Physicists Coalition for Nuclear Threat
Reduction, http://physicistscoalition.org/, a project to engage and activate the global physics community, which is headquartered
at the Princeton University Program on Science and Global Security. |
| Mar 11 |
Hui Cao Yale University |
Anderson localization marks a halt of diffusive propagation in disordered systems,
and it exists for various types of waves. Despite extensive studies over the past
40 years, Anderson localization of light in three dimensions remained elusive, leading
to the question of its very existence. Recent computational advances enabled large-scale
numerical calculations, allowing us to conduct brute-force simulations of light transport
in fully disordered three-dimensional systems with unprecedented dimension and refractive
index difference. We show numerically three-dimensional localization of vector electromagnetic
waves in in random packings of metallic spheres, in sharp contrast to its absence
in the dielectric systems. We also identify a mobility edge that separates diffusive
transport and Anderson localization, and reveal a sharp transition from diffusion
to localization for light. Our work opens a wide range of avenues in both fundamental
research related to Anderson localization and potential applications using three-dimensional
localized light. |
| Mar 18 | -- | No Colloquium. Spring Break. |
| Mar 25 |
Thomas Allison Stony Brook University |
Our conceptual pictures and theoretical formulations regarding the dynamics of quasi-particles in crystalline materials, such as electrons, holes, and excitons, are formulated in momentum space. For example, when we think about how a semiconductor absorbs or emits light, we draw the band structure and arrows connecting the valence band and conduction band, along with scattering mechanisms characterized by energy and crystal momentum. However, our observables of these phenomena involve integrals over many states in momentum space, and are also blind to so-called “dark” states that do not interact with light. Significant interpretation is then required to connect optical spectra to the underlying momentum-space dynamics, and it is easy to get these interpretations wrong. Recently, breakthroughs in technology for time- and angle-resolved photoemission (tr-ARPES),
developed at Stony Brook and a few other labs, make direct momentum-space snapshots
of electron dynamics across the full Brillouin zone no longer just a theoretical construct
but a recorded reality. In this talk, I will discuss both the optical science behind
these recent breakthroughs in tr-ARPES and recent results from my lab. Specifically,
I will discuss pseudo-spin dynamics in graphene, valley polarization dynamics in monolayer
WS2, and the mixture of metastable exciton states produced in MoSe2/WS2 heterostructures after above-bandgap excitation. Direct visualization of momentum-space
wave functions enables new discoveries unseen in previous measurements in each case,
but this only represents a small glimpse of the science now accessible with these
new techniques. Finally, I will present an outlook for some upcoming experiments and
where the field is going with further advances in the techniques. |
| Apr 1 |
Christoph Paus Massachusetts Institute of Technology |
In 2020, the U.S. and CERN signed a bilateral agreement enabling U.S. participation in the Feasibility Study for a Future Circular Collider, which CERN Council initiated in 2021 to evaluate the cost, technical design, and site feasibility. This study will conclude in March 2025. In this presentation I will take a look at this daring project, which is bound to
take over the precision and energy frontier for decades to come. I will discuss its
major goals, potential and opportunities for collaboration. |
| Apr 8 |
Katerina Chatziioannou California Institute of Technology |
Detections of neutron stars in binaries through gravitational waves offer a novel
way to probe the properties of extremely dense matter. In this talk I will describe
the properties of the signals we have observed, what they have already taught us,
and what we expect to learn in the future. I will also discuss how information from
gravitational waves can be combined and compared against other astrophysical and terrestrial
probes of neutron star matter to unveil to the properties of the most dense material
objects that we know of. |
| Apr 15 |
Undergraduate Colloquium |
|
| Apr 22 |
Thomas Roser Brookhaven National Laboratory |
In our world of increasing Global Warming and extreme weather events this talk explores
the steps that can be taken to build and operate accelerators and colliders in a more
sustainable and responsible way. After a general discussion of sustainability I will
describe the work of the ICFA Panel on Sustainable Accelerators and Colliders and
the on-going planning efforts towards more sustainable future large accelerators. |
| Apr 29 |
David Goldhaber-Gordon Stanford University |
When two atomically-thin layers of a material are stacked one atop each other, with a relative twist angle between them, properties can emerge that bear little resemblance to the behavior of the individual layers. Though much can be predicted and designed about such structures, I will share two vignettes about how my students aimed for a particular behavior but found something quite different. The first led to the discovery of the first experimentally-known "orbital magnet", a ferromagnet in which the tiny microscopic magnets that align with each other are not electron spins but tiny circulating current loops. The second surprise was observing resistance that skyrocketed with the application of a magnetic field, along with other striking electronic properties -- this one took years to figure out, but we've recently explained it. Each of these two surprises turned out to be caused by a structural feature of the
layered stack which had not previously been considered important. Finally, I'll describe
work toward robotic stacking and a newly-developed technique for mapping the structure
of twisted layers, which together might help us get more repeatable control of structure
and thus electronic properties in such twisted systems. |
| May 6 |
Graduate Colloquium |
|
| Date | Speaker | Title & Abstract |
| Aug 27 |
Physics and Astronomy Department Chair |
|
| Sep 3 |
Rachel Bezanson University of Pittsburgh |
NASA's latest great flagship observatory, JWST, was built in part to reveal the earliest
moments of cosmic history. In the 2 years since it began releasing data to the public,
JWST has enthralled scientists and the public alike with the incredible images and
spectroscopic information from astronomical objects as nearby as our solar system
and beyond to the most distant reaches of the Universe. The astronomical community
has set distance records, found galaxies that may be significantly larger than models
suggest could exist, and demonstrated that in some cases galaxy and supermassive black
hole formation was earlier and more rapid than we had ever expected. In this talk,
I will highlight some of the exciting results from the UNCOVER (Ultradeep NIRSpec
and NIRCam ObserVations before the Epoch of Reionization (https://jwst-uncover.github.io/) Treasury program. The UNCOVER program began in November 2022 with ultradeep NIRCam
images of the Abell 2744 cluster ("Pandora's cluster") and within the same observing
cycle targeted ~700 JWST-selected objects with deep NIRSpec PRISM spectra. These rich
data have enabled spectroscopic studies of anticipated galaxy populations, including
some of the most distant galaxies at cosmic dawn and the lowest mass systems that
reionized the Universe. However, the same dataset has also revealed the unexpected,
including extreme early supermassive black holes, dusty quiescent galaxies, and even
low mass brown dwarfs in our own Milky Way. When combined with the multitude of additional
multiwavelength data from other early JWST observations and HST, Chandra, ALMA, the
VLT, etc., UNCOVER has helped to establish Abell 2744 as one of the premiere extragalactic
fields. |
| Sep 10 |
Chiara Mingarelli Yale |
Galaxy mergers are a standard aspect of galaxy formation and evolution, and most large
galaxies contain supermassive black holes. As part of the merging process, the supermassive
black holes should in-spiral together and eventually merge, generating a background
of gravitational radiation in the nanohertz to microhertz regime. An array of precisely
timed pulsars spread across the sky can form a galactic-scale gravitational wave detector
in the nanohertz band. I describe the current efforts to develop and extend the pulsar
timing array concept, together with recent evidence for a gravitational wave background,
and efforts to constrain astrophysical phenomena at the heart of supermassive black
hole mergers. |
| Sep 17 |
David Gross KITP |
I shall discuss the past, present and future of this remarkable theory. |
| Sep 24 |
Karsten Heeger Yale |
Neutrinos are among the most abundant particles in the Universe and may hold the key
to understanding the predominance of matter over antimatter in the cosmos. The search
for neutrinoless double beta decay is a unique way to probe the nature of neutrinos.
Observing this process would demonstrate that the neutrino is its own antiparticle
(Majorana particle), provide new means for generating mass, and would revise our foundational
understanding of physics. CUORE, the Cryogenic Underground Observatory for Rare Events,
has created the coldest cubic meter in the known Universe for a bolometric search
for this rare decay. In this talk, I will report on recent results from CUORE and
the plans for CUPID, a ton-scale upgrade with neutrino mass sensitivity beyond the
inverted mass ordering. |
| Oct 1 |
Ken Dill Stony Brook University |
How did the first living cells come into being from the earth’s molecular soup about
4 billion years ago? It appears to have been an unrepeatable singularity. Despite
much speculation – maybe RNA molecules came first, or proteins, or chemical networks
– there’s not yet a consensus origins story. We’ve taken a new look, from a physics
perspective. The first step must have been a non-equilibrium adaptive and stable
stochastic process that drove an irreversible transition. Also, although the question
of how today’s biological proteins could have arisen from random sequences seems like
a “needle-in-a-haystack” problem, such problems are often readily solved through the
statistical physics of disorder-to-order processes. This new look is leading to
specific experimental predictions, and our recent experiments look promising. |
| Oct 8 |
Eden Figueroa Stony Brook University |
The Quantum Internet (QI) concept was proposed in the late 2000s, inspired by advancements in network technologies and light-matter quantum interfaces. It is based on interconnecting quantum nodes, including quantum memories (QM) and entanglement sources, to distribute quantum entanglement between quantum network (QN) nodes. To achieve the benefits of the QI, such as long-distance entanglement distribution and networked quantum computing, one must integrate quantum operations across a collection of interconnected Hamiltonians, together with contemporaneous networking principles and layered architectures. In this colloquium, we will present our implementation of a quantum-enabled Internet
(QEI) based on this physics-centric layered network architecture. We will introduce
a quantum network paradigm adopting an operational hierarchy allowing the execution
of QN processes by simultaneously driving sets of remotely located Hamiltonians at
QN nodes. We will also present the experimental realization of these concepts using
a real-world quantum network connecting Stony Brook University, Brookhaven National
Laboratory and the Commack Data Center. Lastly, we will discuss the Stony Brook –
Columbia -Yale quantum network (SCY-QNet), which is an expansion of our current efforts,
aimed to create a 10-node, 350 km long quantum internet prototype connecting advanced
quantum processing units. |
| Oct 15 | -- | No Colloquium. Fall Break. |
| Oct 22 |
Stefano Spagna Quantum Design |
Industrial Physics brings together people, education, and scientific principles in a powerful synergy that drives technological products and services essential to today’s U.S. economy. This presentation highlights one company’s leadership in cryogenic materials characterization platforms and explores how its success stems from identifying emerging technologies and transforming them into specialized measurement instruments tailored to solve real world challenges faced by the research community. A key factor of this success story involves partnerships with academic institutions and leading technology companies, nurturing innovative ideas from cutting-edge research conducted in labs worldwide. These collaborations benefit universities in a concrete way by modernizing and restructuring undergraduate and graduate laboratory research and education, developing experiment curricula that reflect the latest research and technological advancements, and reinforcing a commitment to innovation in STEM education. In this presentation, we will also discuss specific innovations in fields ranging from magneto-optics to correlative microscopy. We will delve into the design elements and workflows made possible by Quantum Design’s award-winning Atomic Force and Scanning Electron Microscopy (AFM-SEM) systems, illustrating their importance in materials research, including studies of 2D materials, nanoparticles, magnetic nanorods, failure analysis, and semiconductor research. Additionally, we will explore how the emerging field of AFM-SEM correlative microscopy enables scientists to analyze a broader range of samples by leveraging the complementary strengths of each technique, generating a wider array of nanoscale information. Key words: Industrial Physics, STEM education, AFM, SEM, Correlative microscopy, nanoparticles, |
| Oct 29 |
Swati Singh University of Delaware |
Abstract: When properly engineered, simple quantum systems such as harmonic oscillators or spins can be excellent detectors of feeble forces and fields. Following a general introduction to this fast-growing area of research, I will focus on using optomechanical systems as sensors of weak acceleration and strain fields. Ultralight dark matter coupling to standard model fields and particles would produce a coherent strain or acceleration signal in an elastic solid. I will discuss the feasibility of searching for this signal using various optomechanical systems. I will also show that current mechanical systems have the sensitivity to set new constraints on scalar field candidates for dark energy. Finally, I will briefly overview the promise of quantum noise limited detectors in the search for beyond the standard model physics. Brief Bio: Swati Singh is an associate professor in the Department of Electrical and Computer
Engineering, Material Science and Engineering, and Physics at the University of Delaware.
Her theoretical work spans a wide range of quantum systems: atomic gases, optomechanical
oscillators, solid-state qubits, and superfluid helium. Her recent work involves investigating
novel applications for quantum sensors, such as detecting gravitational waves, dark matter, and dark energy. She is the recipient of the NSF CAREER award and ITAMP Postdoctoral fellowship.
Previously, she was a postdoc at Harvard University, a Ph.D. student at the University
of Arizona, a Master's student at the University of British Columbia, and an undergraduate
at McMaster University. |
| Nov 5 | -- | No Colloquium. Election Day. |
| Nov 12 |
Jesus Perez-Rios Stony Brook University |
The three-body problem, such as three bodies interacting through gravity, is paramount
in fundamental and mathematical physics. It is well-known that it has no closed solution,
and the dynamics is chaotic. The equivalent problem in chemical physics is a termolecular
reaction in which three bodies (chemicals) collide, yielding a bound state between
two bodies while the third one gets the excess kinetic energy. Termolecular reactions
are essential to many chemical and physical systems, from ultracold atoms, determining
the system's stability, to plasma physics, explaining the recombination dynamics.
In this talk, we will present our methodology for treating termolecular reactions
and its application to several intriguing scenarios: cold chemistry, atmospheric physics,
and geochemistry. Within cold chemistry, we will show the current understanding of
ion-atom-atom recombination reactions essential to understanding the stability of
cold ions for applications as a quantum simulator. On the atmospheric physics front,
we will present our results on the ozone formation reaction, one of the most relevant
reactions in atmospheric physics. Regarding geochemistry, we will discuss our latest
results on the sulfur cycle reactions essential to understanding the great oxygenation
event, that moment in the history of our planet when the living organism transitioned
from anaerobic to aerobic. Finally, we will present some of our efforts toward the
theoretical understanding of cluster physics, solvation chemistry, and nucleation
dynamics. |
| Nov 19 |
Eun-Ah Kim Cornell |
Decades of efforts by the quantum materials research community drove a "data revolution."
Modern experimental modalities produce high-dimensional data in large volumes. Unprecedented
control and new facilities imply new dimension and new knobs, such as time-resolved
probing or scanning probing. Moreover, massive amounts of high-throughput ab-initio
data and curated experimental data are becoming accessible to researchers. Much needed
are data-centric approaches that accelerate discoveries from these data through synergetic
interaction with expert human researchers' insights. A synergy between data science
and quantum materials research is essential for such endeavors to result in scientific
progress. I will present cases of fruitful collaborations that led to new insights
and started to shape an approach to data sets of the new era. Specifically, I will
discuss how to use unsupervised learning to discover new physics from large volumes
of evolving data and how to use supervised learning to uncover descriptors of emergent
properties from limited volume of expertly curated data. |
| Nov 26 | -- | No Colloquium. Thanksgiving Week. |
| Dec 3 | -- | TBA. |
| Date | Speaker | Title & Abstract |
| Jan 23 | -- | TBA. |
| Jan 30 |
JoAnne Hewett Director of Brookhaven National Laboratory |
Brookhaven National Lab – a close partner with Stony Brook University – has an exciting
and diverse science program. The lab’s research spans the science spectrum from pulling
together broad teams to construct and operate large facilities, to individual researchers
with valuable contributions to the lab’s priorities. In this talk, I will describe
our enduring priorities and future science initiatives, highlighting collaboration
with Stony Brook scientists. |
| Feb 6 |
Alexei Koulakov Cold Spring Harbor Laboratory |
We have entered a golden age of artificial intelligence research, driven mainly by
the advances in the artificial neural networks over the last decade or so. Applications
of these techniques—to machine vision, speech recognition, autonomous vehicles, natural
language, and many other domains—are coming so quickly that many observers predict
that the long-elusive goal of “Artificial General Intelligence” (AGI) is within our
grasp. However, we still cannot build a machine capable of building a nest, stalking
prey, or loading a dishwasher. I will describe how evolution may have shaped the algorithms
that the brain is using to solve some of these challenging problems. |
| Feb 13* |
Jocelyn Bell Burnell Oxford University |
In this talk I describe the discovery of pulsars (pulsating radio stars) and what we know about them today. * This is the Della Pietra General Public Lecture, and will be held in the Della Pietra Family Auditorium - 103 on Tuesday, Feb 13 at 5:00pm, instead of the usually scheduled colloquium time and location. |
| Feb 20 |
Mengkun Liu Stony Brook University |
In contemporary condensed matter physics and photonics, four length scales are fundamentally interesting and intertwined: 1) Polaritonic wavelength in infrared (IR) and terahertz (THz) frequencies (e.g. plasmon, phonon, exciton, or magnon polaritons), which defines the scale of the light confinement and light-matter interaction; 2) Magnetic lengths, (with he magnetic field), which defines the restricted electron motion in a B field; 3) Diffusion length of the hot carriers at interfaces and the edges, which defines the scale of energy relaxation, and 4) Periodicities of superlattices induced by moiré engineering, which defines the energy scale of emerging quantum phases. For instance, the commensurability of the magnetic lengths (e.g. ~10 nm for graphene at 7T) and superlattice constant (e.g. ~10 nm for twisted bilayer graphene at ‘magic angle’) could lead to exotic fractal quantum states. In this talk, I report 1) A new type of optical spectroscopy technique (aka. Landau level nanoscopy) to tackle all four above-mentioned ‘lengths’ simultaneously in one experiment; 2) A new type of infrared polaritons that can be tuned via magnetic field; 3) A nanoscale probe of the many-body physics through the excitations of magnetoexcitons in graphene across the allowed and forbidden optical transitions. Our approach establishes the Landau-level nanoscopy as a versatile platform for exploring magneto-optical effects at the nanoscale. Our preliminary research also sets the stage for future spectroscopic investigations of the topological and chiral photonic phenomena in complex quantum materials using low-energy photons. Mengkun Liu (Ph.D. 2012 Boston University) is an associate professor at the Department
of Physics and Astronomy of Stony Brook University (since Jan. 2015). His postdoc
research was at UC San Diego from 2012-2014. His research interests include the physics
of correlated electron systems, low-dimensional quantum materials, infrared and terahertz
nano-optics, and ultrafast time-domain spectroscopy. Prizes include the Moore EPI
award (2023), NSF career award (2021), and Seaborg Institute Research Fellowships
at Los Alamos National Lab (2009, 2010). |
| Feb 27 |
Neelima Sehgal Stony Brook University |
CMB experiments have contributed powerful constraints on the fundamental physics of
the Universe. Upcoming CMB experiments such as the Simons Observatory and CMB-S4 are
poised to extend this progress even further. However, CMB experiments still have a
wealth of information to offer beyond these near-term facilities regarding the properties
of dark matter, inflation, and light relic particles. In particular, a much lower-noise
and higher-resolution wide-area CMB survey can cross a number of critical fundamental
physics thresholds and open a relatively untapped window of small-scale, late-time
CMB anisotropies. Here I will discuss CMB-HD, a Stage-5 CMB facility, and the discoveries
it can enable. |
| Mar 5 |
No Colloquium. |
-- |
| Mar 12 |
|
-- |
| Mar 19 |
Gianfranco Bertone University of Amsterdam |
I will start with an overview of the status of dark matter searches and of the prospects
for uncovering its nature in the next decade. I will then focus on the interplay between
dark matter, black holes, and gravitational waves, and discuss the prospects for characterizing
and identifying dark matter using gravitational waves, covering a wide range of candidates
and signals. Finally, I will present some new results on the detectability of dark
matter overdensities around black holes in binary systems, and argue that future interferometers
may enable precision studies of the dark matter distribution and particle properties. |
| Mar 26 |
Smitha Vishveshwara University of Illinois Urbana-Champaign |
From ancient monuments to modern day films, the confluence of the arts and physics
has resulted in creations that have led to a deeper understanding of nature, to friendly
and enchanting ways of perceiving science, to crafting new artistic dimensions, to
technological progress, and to pure fun! In this talk, I will describe the educational
power of such confluences and recount some of our experiences. In a project-based
interdisciplinary course entitled Where the Arts meets Physics, we bring alive the
universe and the quantum world through installations and performance – cosmic canopies
housing black hole mergers, Warhol versions of Bohr-Einstein debates, and more. Collaborations
with theater, music, dance, and circus have led to several performance pieces that
explore the magic and beauty of the quantum world and our cosmos: Quantum Voyages;
Quantum Rhapsodies; The Joy of Regathering; Cosmic Tumbles, Quantum Leaps, and more.
I will share glimpses of the science, stories, the process behind the making of these
pieces, and the productions across the globe both in-person and virtually for pandemic
times. I will conclude with visions of how these adventures will continue on over
the UNESCO endorsed 2025 International Year of the Quantum. |
| Apr 2 |
Smadar Naoz University of California Los Angeles |
The detection of Gravitational Wave emission, of the merger of two black holes, has
forever transformed the way we sense our universe. Future detectors, such as the Laser
Interferometer Space Antenna (LISA), will open the opportunity to detect the merger
of a small (tens of solar mass) black hole with a big, supermassive black hole (SMBH,
millions to billions of solar mass). These events are called extreme-mass-ratio inspirals
(EMRIs). The popular formation channel for these promising events involves weak two-body
kicks from the population of stars and compact objects surrounding the SMBH that can
change the small black hole's orbit over time, driving it into the SMBH. On the other
hand, perturbations from SMBH companions can excite the SMBH to high eccentricities,
thereby forming EMRIs. In this talk, I will demonstrate that combining these two processes
is essential to comprehending the dynamics of EMRI progenitors. I will also show that
EMRIs are naturally formed in SMBH binaries with higher efficiency than either of
these processes considered alone. Thus, it is truly raining black holes! This scenario
results in a large stochastic background for future GW detectors such as LISA. Finally,
I will demonstrate the implications that this physical mechanism has on tidal disruption
events. |
| Apr 9 |
-- |
Undergraduate Colloquium. |
| Apr 16 |
David J. Wineland Phillip H. Knight Distinguished Research Chair, |
For many centuries, and continuing today, a primary application of accurate clocks
is for precise navigation. For example, GPS enables us to determine our distance from
the (known) positions of satellites by measuring the time it takes for a pulse of
radiation emitted by each satellite to reach us. The more accurately we can measure
this duration, the more accurately the distance is known. When performed with a network
of satellites, we can find our position in 3 dimensions. Atoms absorb electromagnetic
radiation at precise discrete frequencies. Knowing this, a recipe for making an atomic
clock is simple to state: we first need an oscillator to produce the radiation and
an apparatus that tells us when the atoms maximally absorb it. When this condition
is met, we can simply count cycles of the oscillator; the duration of a certain number
of cycles defines a unit of time. For example, the internationally agreed on definition
of the second corresponds to 9,192,631,770 oscillations of the radiation corresponding
to the Cesium “hyperfine” transition. Today, the most precise clocks count cycles
of radiation corresponding to optical wavelengths, or around a million billion cycles
per second. To achieve high accuracy, many interesting effects, including those due
to Einstein’s relativity, must be accounted for. In this talk I will focus on atomic
clocks derived from optical transitions in atomic ions. |
| Apr 23 |
Chris Quigg Fermilab |
A richly illustrated tour of a century of high-energy collisions featuring people,
ideas, and stories, free of dense equations and impenetrable jargon. |
| Apr 30 |
-- |
Graduate Colloquium. |
| Date | Speaker | Title & Abstract |
|
Sep 5 |
Stony Brook University |
|
|
Sep 12 |
Chris Greene Purdue University |
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. |
|
Sep 19 |
Nobel Prize Recipient, 2012 |
|
|
Sep 26 |
Jan Bernauer Stony Brook University |
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 |
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. |
|
|
Oct 17 |
Gregory Falkovich Weizmann Institute of Science |
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 |
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 |
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. |
|
Nov 7 |
Cyrus Dreyer Stony Brook University |
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 |
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 |
|
|
Nov 28 |
No Colloquium |
|
|
Dec 5 |
Keshav Dani Okinawa Inst. of Sci. & Tech. Graduate University |
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) |
| Date | Speaker | Title & Abstract |
|
Feb 7 |
Alyson Brooks Rutgers |
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 |
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). |
|
Feb 21 |
Zoe Yan Princeton |
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 |
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 |
-- |
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Mar 14 |
-- |
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|
Mar 21 |
Monica Plisch Director of Programs, American Physical Society |
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 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 |
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 |
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 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 |
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 |
Stony Brook University |
|
| Date | Speaker | Title & Abstract |
|
Sep 6 |
Professor of Physics, Emeritus, Distinguished Professor of Physics, Nobel Laureate, 2017 |
|
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Sep 13 |
Stony Brook University |
|
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Sep 20 |
-- |
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Sep 27 |
-- |
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|
Oct 4 |
Mariangela Lisanti Princeton |
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 |
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Oct 18 |
Peter Denton Brookhaven National Laboratory |
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 |
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 |
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.
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Nov 8 |
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Nov 15 |
Jen Cano Stony Brook University |
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 |
-- |
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Nov 29 |
Giacinto Piacquadio Stony Brook University |
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 |
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. |
| Date | Speaker | Title & Abstract |
|
Feb 1 |
Navid Vafaei-Najafabadi Stony Brook University |
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 |
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 |
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. |
|
Feb 22 |
Murray Holland University of Colorado Boulder |
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. |
|
Mar 1 |
-- |
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Mar 8 |
Laura Cadonati Georgia Institute of Technology |
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 |
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. |
|
Mar 29 |
Dmitry Tsybychev Stony Brook University |
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. |
|
Apr 5 |
Heather Gray Berkeley |
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 |
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. |
|
Apr 19 |
Mark Palmer Brookhaven National Laboratory |
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. |
|
Apr 26 |
John Wilkerson University of North Carolina |
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. |
|
May 3 |
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|
Date |
Speaker |
Title & Abstract |
|
Aug 31 |
Matthew Dawber Stony Brook University |
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 |
Stony Brook University |
|
|
Sept 14 |
Gregory Falkovich Weizmann Institute |
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 |
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 |
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 |
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 |
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. |