September 10 Distinguished University Professor Lecture | Ted Jacobson, University of Maryland Hawking radiation in a laboratory!? Einstein's theory of gravity opened Pandora's box of warped spacetime in 1915, and out popped the black hole, confusing and delighting (or maddening) physicists ever since. In the early 1970's it was discovered that black holes have entropy and temperature, and decay by Hawking radiation like radioactive whirlpools in the spacetime river. Two persistent puzzles have resulted from this discovery: the information paradox and the transPlanckian problem. To bring some of this down to earth, Unruh in 1980 conceived of a black hole analog, formed by a quantum fluid, which might one day be studied in a laboratory. That day has now come...probably. In the last few years, Jeff Steinhauer has carried out a number of experiments on Bose-Einstein condensates of rubidium atoms, configured to emulate a black hole, and reported on the observation of thermal phononic Hawking radiation and its quantum entanglement with phonons inside the sonic black hole. In this colloquium I will describe these ideas and experiments, as well as simulations that have been carried out in order to help understand what has so far been observed. |
September 19 ***THURSDAY***, in 1101 A. James Clark Hall The Paint Branch Distinguished Lecture in Applied Physics | Donna Strickland, University of Waterloo
Hosted by Tom Murphy From Nonlinear Optics to High- Intensity Laser Physics The laser increased the intensity of light that can be generated by orders of magnitude and thus brought about nonlinear optical interactions with matter. Chirped pulse amplification, also known as CPA, changed the intensity level by a few more orders of magnitude and helped usher in a new type of laser-matter interaction that is referred to as high-intensity laser physics. In this talk, I will discuss the differences between nonlinear optics and high-intensity laser physics. The development of CPA and why short, intense laser pulses can cut transparent material will also be included. I will also discuss future applications. Donna Strickland is one of the recipients of the Nobel Prize in Physics 2018 for co-inventing Chirped Pulse Amplification with Dr. Gérard Mourou, her PhD supervisor at the time of the discovery. She earned her PhD in optics from the University of Rochester and her B. Eng. from McMaster University. Dr. Strickland was a research associate at the National Research Council Canada, a physicist at Lawrence Livermore National Laboratory and a member of technical staff at Princeton University. In 1997, she joined the University of Waterloo, where her ultrafast laser group develops high-intensity laser systems for nonlinear optics investigations. She is a recipient of a Sloan Research Fellowship, a Premier’s Research Excellence Award and a Cottrell Scholar Award. She served as the president of the Optical Society (OSA) in 2013 and is an OSA Fellow and an SPIE Fellow. |
September 24 | Maissam Barkeshli, University of Maryland
Splitting the electron: New aspects of electron fractionalization in quantum matter |
October 1 | Shamit Kachru, Stanford University
Hosted by Anson Hook & Raman Sundrum Adventures in Quantum Critical MetalsNature has provided us with several intriguing systems where, apparently, Landau’s Fermi liquid theory breaks down — with striking consequences for low energy physics. In this talk I describe, in an elementary way, (highly idealized) attempts to model these quantum critical systems using the techniques of quantum field theory. |
October 8 | Meenakshi Narain, Brown University
Hosted by Sarah Eno Postcards from the Future — The Physics Landscape at the High-Luminosity LHC The discovery of the Higgs Boson by the ATLAS and CMS experiments at the Large Hadron Collider (LHC) in Geneva, Switzerland, was one of the most important and exciting moments in particle physics. The field of particle physics has transitioned to a new phase that presents us with a new opportunity to gain a deeper understanding of the fundamental nature of matter and our universe. I will discuss some of these implications, which inform the efforts to figure out the roadmap of particle physics in the coming decades. Starting around 2026, the High-Luminosity LHC (HL-LHC) will deliver proton-proton collisions at a center-of-mass energy of \sqrt{s} = 14 TeV. I will summarize the studies from a comprehensive campaign mounted in 2018, to understand the physics reach of the experiments at the HL-LHC and a possible higher energy LHC (HE-LHC) at 27 TeV. |
October 15 Shih-I Pai Lecture 3 - 3:50 pm: Reception in the James A. Yorke Rotunda, William E. Kirwan Hall
4 - 5:00 pm: Lecture in 1412 John S. Physics Building | Jenann Ismael, Columbia University
Hosted by Christopher Jarzynski Information, Time, and Life The differences between past and future frame every aspect of our experience of the world. It is a remarkable fact that research that began in the mid-nineteenth century and was originally focused on trying to derive the phenomenological asymmetries embodied in the second law of thermodynamics from the time-symmetric laws of classical mechanics turned into a very general account of the sources of temporal asymmetry in our world. So a conversation that started by being about why (for example) gas will disperse to fill an open container, turned into a conversation about why we remember the past but not the future, why time seems to flow from past to future, and why we can affect the future but not the past. There is much that remains to be understood, but we can assemble the pieces that we have into a picture that has intelligible contours and gives us deep insight not only into the nature of time, but the asymmetries that structure living processes, and our own place in the universe. I'll sketch the elements of this picture in broad strokes, highlighting the role of information. |
October 22 | Raju Venugopalan, Brookhaven National Lab & Stony Brook University Hosted by Paulo Bedaque The glue that binds us all: lifting the veil on emergent universal dynamics in nature's strong force at high energies Massless gluons are responsible for nearly all of the mass of the visible universe. After a brief survey of their remarkable properties, we outline how gluon matter at high energies can be described by a strongly correlated many-body theory with universal dynamics that bears striking parallels to systems in statistical mechanics and to a memory effect carried by gravitational waves. When heavy nuclei collide at ultra relativistic energies, Weibel-like instabilities drive the matter to decohere and flow to a nonthermal fixed point before forming a perfect fluid on parametrically long time scales. This nonthermal fixed point of the hottest terrestrial fluid (T= trillion Kelvin) is universal and can be quantum simulated by cold atomic gases (T=nano Kelvin). |
October 29 Distinguished Scholar-Teacher Lecture | Dan Lathrop, University of Maryland
Machine learning and the scientific methodScience is now performed with people and computers working together on many if not most of our tasks. Outside of academia, machine learning tools (voice recognition, image recognition, etc.) permeate our lives through the technology we use. Those machine learning tools are also undergoing widespread adoption into scientific exploration. In this talk, I will try to tackle a few puzzling questions: machine learning -- what is it / what is it not? The scientific method -- what is it / what is it not? And finally: is machine learning a scientific method? Along the way we will make stops at various curious and interesting corners such as the meaning of understanding, creativity, the double-pendulum, the three-body problem, neurodiversity, and how people pick the scientific projects. |
November 5
| Emanuel Derman, Columbia University
Hosted by Victor Yakovenko A Stylized History of Quantitative Finance The evolution of a quantitative approach to finance has proceeded through many small but significant steps and occasional large epiphanies. This talk outlines how, over the past 70 years, financial models have quantified the notion of derivatives, diffusion, risk, volatility, the riskless rate, diversification, hedging, replication, and the principle of no riskless arbitrage. Bio: Emanuel Derman is a professor at Columbia University, where he directs their program in financial engineering. He was born in South Africa but has lived most of his professional life in Manhattan. He started out as a theoretical physicist, doing research on unified theories of elementary particle interactions. At AT&T Bell Laboratories in the 1980s he developed programming languages for business modeling. From 1985 to 2002 he worked on Wall Street where he co-developed the Black-Derman-Toy interest rate model and the local volatility model. He is the author of The Volatility Smile (Wiley, 2017) and Models.Behaving.Badly (Free Press 2011), one of Business Week’s top ten books of 2011. He is also the author of My Life As A Quant (Wiley 2004), also one of Business Week's top ten of 2004, in which he introduced the quant world to a wide audience. |
November 12 | Kiyong Kim, University of Maryland
Physics and engineering of strong terahertz pulse generation Terahertz science and technology is of great current interest due to its potential applications in bio-medical imaging and spectroscopy, chemical/explosive detection, wireless communication, security scanning, and plasma diagnostics. However, few sources and detectors exist in the terahertz frequency band. This leaves a major gap between the optical and microwave regions, for which new high-power terahertz sources would have a major impact. One promising source pioneered by my group and now adopted worldwide is based on controlling the laser-driven orbits of free electrons liberated by high field ionization of gases. In this talk, I will present recent experiments that provide a better understanding of this process, enabling us to achieve a world record in THz generation efficiency. This source will open up new opportunities to explore extreme terahertz-driven nonlinear processes in atoms, molecules, and plasmas. |
November 19 | Félicie Albert, Lawrence Livermore National Laboratory
Hosted by Howard Milchberg X-ray sources from laser-plasma acceleration: development and applications for high energy density sciences Bright sources of x-rays, such as synchrotrons and x-ray free electron lasers (XFEL) are transformational tools for many fields of science. They are used for biology, material science, medicine, or industry. Such sources rely on conventional particle accelerators, where electrons are accelerated to gigaelectronvolts (GeV) energies. The accelerating particles are also wiggled in magnetic structures to emit x-ray radiation that is commonly used for molecular crystallography, fluorescence studies, chemical analysis, medical imaging, and many other applications. One of the drawbacks of synchrotrons and XFELs is their size and cost, because electric field gradients are limited to about a few 10s of MeV/M in conventional accelerators.
This seminar will review particle acceleration in laser-driven plasmas as an alternative to generate x-rays. A plasma is an ionized medium that can sustain electrical fields many orders of magnitude higher than that in conventional radiofrequency accelerator structures. When short, intense laser pulses are focused into a gas, it produces electron plasma waves in which electrons can be trapped and accelerated to GeV energies. This process, laser-wakefield acceleration (LWFA), is analogous to a surfer being propelled by an ocean wave. Betatron x-ray radiation, driven by electrons from laser-wakefield acceleration, has unique properties that are analogous to synchrotron radiation, with a 1000-fold shorter pulse. This source is produced when relativistic electrons oscillate during the LWFA process.
An important use of x-rays from laser plasma accelerators we will discuss is in High Energy Density (HED) science. This field uses large laser and x-ray free electron laser facilities to create in the laboratory extreme conditions of temperatures and pressures that are usually found in the interiors of stars and planets. To diagnose such extreme states of matter, the development of efficient, versatile and fast (sub- picosecond scale) x-ray probes has become essential. In these experiments, x-ray photons can pass through dense material, and absorption of the x-rays can be directly measured, via spectroscopy or imaging, to inform scientists about the temperature and density of the targets being studied.
Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344, supported by the LLNL LDRD program under tracking code 13-LW-076, 16-ERD-024, 16-ERD-041, supported by the DOE Office of Fusion Energy Sciences under SCW 1476 and SCW 1569, and by the DOE Office of Science Early Career Research Program under SCW 1575. |
November 26 | Xiangdong Ji, University of Maryland Exploring a quantum world travelling at the speed of light What would the world look like if one travels at the speed of light？We began to seriously answer this type of question when studying the internal structure of the proton in high-energy scattering, following the pioneering work of R. P. Feynman in 1969. With a high-energy Electron-Ion Collider (EIC) soon to be built in United States, we are about to get precise 3D images of a light-travelling proton, and to check them against exa-scale Euclidean quantum chromodynamic calculations through a novel theoretical construct: Large Momentum Effective Theory. |
December 3 | John Doyle, Harvard University
Hosted by Ron Walsworth Trapped laser-cooled molecules for particle physics using quantum tools Due to the versatility and controllable complexity of cold polar molecules, they are a powerful platform for precision measurement searches of physics beyond the standard model (BSM). This, and their use for quantum information applications, has led to intense efforts to control molecules at the quantum level. In particular, precision searches for new particle physics beyond the Standard Model (BSM), including new cosmology-related physics, is an area of significant focus for the physics community. The most recent ACME experiment, which probes for the electron electric dipole moment, is sensitive to T-violating physics due to particles with masses up to 30 TeV, which is a mass scale already well beyond the reach of particle colliders. Thus, EDM experiments, which broadly probe new CP-violating physics, are an important complement collider experiments. Several EDM experiments currently use heavy diatomic molecules (e.g. YbF , HaF+ , ThO) to probe this BSM physics, Diatomic molecules are being planned for use in several next-generation and new experiments searching for BSM physics. I will give an update on the ACME EDM experiment, which last year produced a new limit on the electron EDM and is moving forward with another upgrade. I will also discuss possible future experiments using ultracold polyatomic molecules such as YbOH and YbOCH$_3$. It is predicted that when laser-cooled and trapped optically, such species will provide long coherence times, opening the possibility for future experiments to probe BSM physics at the PeV scale. Finally, use of ultracold molecules for dark matter searches will also be discussed.
John Doyle, Henry B. Silsbee Professor of Physics, Harvard University, grew up in the U.S. and received his bachelor’s degree from the Massachusetts Institute of Technology (M.I.T.) in 1986. After he obtained his Ph.D. degree from, and a short postdoc at, M.I.T., he was appointed as an assistant professor of physics at Harvard University in 1993. John Doyle's research centers on using cold molecules for science ranging from particle physics to bio-analysis to quantum information. Starting with the development a new technique for producing heavy, polar radical molecules in an intense beam, he launched with collaborators searches for physics beyond the Standard Model (BSM) through probing for the electron electric dipole moment. His group also studies fundamental collisional processes in atoms and molecules and develop tools to achieve full quantum control over increasingly complex molecular systems. He is working to realize new techniques to trap and study processes in polyatomic molecules. The Doyle group has pioneered a general technique for cooling and loading atoms and molecules into traps and was the first to laser cool a polyatomic molecule. The group is currently working to put these complex quantum objects into an optical array in order to pursue quantum simulation protocols as well as improve searches for BSM particles. He is the co-Director of the Harvard Quantum Initiative, director of the Japanese Undergraduate Research Exchange Program (JUREP), and co-director of the Harvard/MIT Center for Ultracold Atoms. He has published papers in the areas of ultracold atoms, molecules, spectroscopy, precision measurement, neutrons, and dark matter detection and supervised the PhDs of over thirty students. He is a Humboldt, Fulbright, and American Physical Society Fellow. |
December 10
| Kater Murch, Washington University in St. Louis
Hosted by Alicia Kollár Effective non-Hermitian evolution of a superconducting qubit: probing the topology of a Riemann surface with quantum states |
