Physics & Astronomy Colloquium

Thursdays, 4:00-5:00 pm

Virtual Colloquium Meetings are held via Zoom. Meeting information will be sent in email. You may watch past presentations by clicking the title link when available.

For more information, contact Katsushi Arisaka.

Click here for the 2020-2021 archived Physics & Astronomy Colloquium.

Click here for the 2019-2020 archived Physics & Astronomy Colloquium.

Fall 2021
Thursday, October 7, 2021

Where's Waldo in Biology
Keisuke Goda
University of Tokyo

A fundamental challenge of biology is to understand and exploit the vast heterogeneity of cells, particularly how the spatial architecture of cells is linked to their identity and physiology. However, it is challenging to address the need because it is analogous to “Where’s Waldo (Wally in the UK and Walter in Germany)?” In this talk, I introduce a new type of technology known as “Image-Activated Cell Sorting” that performs real-time, intelligent, image-based sorting of cells at an unprecedented rate of >1000 cells per second (Nitta et al, Cell, 2018; Nitta et al, Nature Communications, 2020). This technology integrates high-throughput fluorescence microscopy, cell focusing, cell sorting, and deep learning on a hybrid software-hardware data-management infrastructure, enabling real-time automated operation for data acquisition, data processing, intelligent decision-making, and actuation. I show a new class of biological, medical, and pharmaceutical applications of the technology.

Biography: Keisuke Goda is a professor in the Department of Chemistry at the University of Tokyo, an adjunct professor in the Institute of Technological Sciences at Wuhan University, and an adjunct professor in the Department of Bioengineering at UCLA. He obtained a B.A. degree from UC Berkeley summa cum laude in 2001 and a Ph.D. from MIT in 2007, both in physics. At MIT, he worked on the development of quantum-enhanced gravitational-wave detectors in the LIGO group. After several years of work on ultrafast photonics and microfluidics at Caltech and UCLA, he joined the University of Tokyo as a professor. His research group focuses on the development of serendipity-enabling technologies based on molecular imaging and spectroscopy together with microfluidics and computational analytics to realize Louis Pasteur’s statement “Chance favors the prepared mind” ( He has published >300 papers and received >30 awards.

Thursday, October 14, 2021

Building a quantum world with trapped ions
Norbert M. Linke
University of Maryland

Trapped ions give us a high degree of detailed control of their various quantum degrees of freedom, which has enabled a large number of experiments in quantum optics, quantum computing, simulation and networking as well as precision metrology and others. We describe our quantum architecture consisting of a linear chain of trapped 171 Yb+ ions with individual laser beam addressing and readout. The collective modes of motion in the chain are used to efficiently produce entanglement between any qubit pair. In combination with a classical software stack, this becomes in effect an arbitrarily programmable, fully connected quantum computer. Over the past five years, we have employed this experiment to demonstrate a variety of quantum algorithms with the help of a community of academic partners, including cross-hardware comparisons with commercially developed systems and digital quantum simulations of models from high-energy physics and other areas. We also use the same level of control to study interesting quantum phenomena using the motional degrees directly, such as exotic para particles. This talk will give recent highlights from both of these approaches and discuss improvements in trap technology for scaling up as well as other ideas for the future.

Norbert M. Linke is a Fellow of the Joint Quantum Institute at the University of Maryland, working on quantum applications with trapped ions, including quantum computing. Born in Munich, Germany, he graduated from the University of Ulm, and received his doctorate at the University of Oxford, UK, working on micro-fabricated ion-traps and microwave-addressing of ions. Before becoming a faculty member in 2019, he spent four years as a post-doc and research scientist in the group of Chris Monroe at the JQI where he led a project that turned a physics experiment into a programmable quantum computer.

Thursday, October 28, 2021

Neutrinos from the Sky and Through the Earth
Kate Scholberg
Duke University

The progress in neutrino physics over the past quarter century has been tremendous: we have learned that neutrinos have mass and change flavor. This discovery won the 2015 Nobel Prize. I will pick out one of the main threads of the story -- the measurement of flavor oscillation in neutrinos produced by cosmic ray showers in the atmosphere, and further measurements by long-baseline beam experiments. In this talk, I will present the latest results from the Super-Kamiokande and T2K (Tokai to Kamioka) long-baseline experiments, and will discuss how the next generation of high-intensity beam experiments will address some of the remaining puzzles.

Thursday, November 4, 2021

Attosecond X-ray movies: the frontier of ultrafast science
Agostino Marinelli
SLAC National Accelerator Laboratory

Electron motion initiates most chemical reactions, and it is an essential component of fundamental light-matter interactions. The dynamics of bound electrons in atoms, molecules and solids happen on very fast time scales, from few femtoseconds down to the sub-femtosecond regime. Therefore, the study of electronic processes on their natural timescales requires pulses of light faster than one femtosecond, and of sufficient intensity to interact with their sample with high probability.

The recent generation of attosecond pulses from an X-ray free-electron laser (at the Linac Coherent Light Source at SLAC) marks the beginning of a new era of attosecond science. XFELs can generate pulses that are more than a million times brighter than conventional attosecond light sources and pave the way to molecular pump/probe movies with sub-fs resolution.

In my talk I will briefly describe the physics of X-ray free-electron lasers and report our recent advances in attosecond X-ray pulse generation. I will then show our recent experimental results in measuring attosecond coherent electron motion in molecules. Finally, I will discuss possible avenues towards brighter and shorter X-ray pulses using the next generation of particle accelerators.

Biography: Ago Marinelli is an assistant professor of Photon Science and Particle Physics and Astrophysics at Stanford University and the SLAC National Accelerator Laboratory. He received his PhD in physics in 2012 from UCLA, working under the supervision of Prof. Jamie Rosenzweig. His research is focused on X-ray free-electron lasers and their applications, with special emphasis on the development of capabilities for ultrafast time-resolved experiments. He is the head of the free-electron laser physics department in the accelerator research division of SLAC and leads the accelerator research and development program at the Linac Coherent Light Source.