The David and Edith Harris Physics Colloquium Series

Fall 2020 Virtual Colloquium Schedule

THURSDAYS // Talks will take place virtually. Info on how to view will be posted shortly.

SEPTEMBER 17, 2020
NIGEL GOLDENFELD
University of Illinois at Urbana-Champaign
Host: Hong Liu

“The life and death of turbulence”

Turbulence is the last great unsolved problem of classical physics. But there is no consensus on what it would mean to actually solve this problem. In this colloquium, I propose that turbulence is most fruitfully regarded as a problem in non-equilibrium statistical mechanics, and will show that this perspective explains turbulent drag behavior measured over 80 years, and makes predictions that have been experimentally tested in 2D turbulent soap films. I will also explain how this perspective is useful in understanding the laminar-turbulence transition, establishing it as a non-equilibrium phase transition whose critical behavior has been predicted and tested experimentally. This work connects transitional turbulence with statistical mechanics and renormalization group theory, high energy hadron scattering, the statistics of extreme events, and even population biology.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

SEPTEMBER 24, 2020
ANDREY VARLAMOV
Institute of Superconductivity and Innovation Materials (SPIN-CNR), Italy
Host: Leonid Levitov

“Physics in the Kitchen”

How does heat conduction in materials impact cooking? What is the difference between baking pizza in a traditional wood oven and an electric one? Why do the boiled meet and the grilled one taste so different? How to predict the cooking time of the soft-boiled duck egg and spaghetti? Why cin-cin with crystal glasses filled by sparkling wine is not accompanied by melodious sound? Why does vodka contain 40% of alcohol? Why does professional barman adjust the degree of coffee beans grinding depending on the weather? This talk will address these and other mysteries of the gastronomic universe.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

OCTOBER 1, 2020
FRANK WILCZEK
MIT
Host: Phiala Shanahan

"Quanta of the Third Kind: Anyons"

According to traditional understanding, quantum particles are either bosons or fermions. This so-called “quantum statistics” has important consequences for their behavior. In the late 70-ies the mathematics of topology was employed to get a deep understanding of quantum statistics, and lead to the realization that in two spatial dimensions there are alternatives beyond bosons and fermions. The new possible particles go under the general name “anyons”, coined in 1982. In 1984 it was demonstrated, theoretically, that quasiparticles in the states of matter known as fractional quantum Hall liquids (FQHL) are fractionally charged anyons. Since then, theoretical and numerical work on states of two-dimensional matter has predicted many types of anyons, and in particular “nonabelian” anyons that could be a powerful resource for quantum computers. Until very recently, experiments on anyons lagged far behind the thriving theoretical and numerical work, but this spring, two independent innovative experiments convincingly observed anyon behavior in the simplest FQHL. The age of experimental anyonics is upon us.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

OCTOBER 8, 2020
MAX SHULAKER
MIT
Host: Peter Fisher

“Transforming Ideas to Reality: Emerging Nanotechnologies from the “Lab” to the “Fab””

At this exact moment when future applications are demanding massive improvements in computing performance, conventional approaches to improving computing are becoming increasingly challenging. Nanosystems – leveraging unique properties of emerging nanotechnologies to realize new systems and architectures – promise to enable the next wave of computing gains for next-generation applications as well as provide the means for developing rich new functionalities that lie beyond the scope of traditional computing today. Yet despite this promise, imperfections and variations inherent in beyond-silicon emerging nanotechnologies have made realizing large-scale integrated systems infeasible. In this talk, I describe how by combining advances across the entire stack – from nanomaterial synthesis to new processing techniques, circuit design methodologies, and architectures – these challenges can be overcome to realize the first large-scale and complex electronic systems leveraging beyond-silicon emerging nanotechnologies. As a case-study, I will describe the journey of transforming carbon nanotubes from an interesting scientific nanomaterial into the foundation for realizing the first beyond-silicon microprocessor built entirely from carbon nanotube transistors – RV16X-NANO, a 16-bit microprocessor based on the RISC-V instruction set. I will conclude by describing how emerging nanotechnologies are beginning to be transferred from the “lab” to the “fab,” promising a new and exciting age for nanoelectronics and computing.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

OCTOBER 15, 2020
JOSEPH CHECKELSKY
MIT

"Synthesizing “Toy Model” Quantum Materials”

Connecting theoretical models for exotic quantum states to real materials is a key goal in quantum material synthesis. Among such theoretical models, a “toy model” is one made deliberately simplistic in order to demonstrate new physical concepts and their underlying mechanisms.  We describe here our recent progress in experimentally realizing “toy model” quantum materials which, in analogy to their theoretical counterparts, are designed to capture simple model systems by lattice and superlattice design.  Examples include the realization of massless and infinitely massive electrons in corner sharing triangular networks predicted for the kagome lattice model, clean-limit 2D superconductivity in natural superlattice materials with potential connections to models of finite momentum pairing and topological superconductivity, and the use of magnetic symmetries to realize nodal electronic structures.  We comment on the prospects for realizing further toy model systems in complex material systems.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

OCTOBER 22, 2020
SARA SEAGER
MIT
Host: Peter Fisher

PAPPALARDO LECTURE

"The Search for Signs of Life Beyond Earth by Way of Atmospheric Biosignature Gases"

For thousands of years, inspired by the star-filled dark night sky, people have wondered what lies beyond Earth. Today, the search for signs of life is a key factor in modern-day planetary exploration, both for in situ exploration of our own Solar System’s planets and moons and for telescope remote sensing of exoplanets orbiting nearby stars. We aim to detect a gas in a planetary atmosphere that might be attributed to life. A suitable “biosignature gas” must: be able to accumulate in an atmosphere against atmospheric radicals and other sinks; have strong atmospheric spectral features; and have limited abiological false positives. The study of biosignature gases is thus intertwined with chemistry. Life on Earth produces thousands of gases. Which gases might be potential biosignatures in an as yet unknown range of possibly exotic exoplanetary environments? New computer simulations and next generation telescopes soon coming on line make us the first generation with the capability to search for signs of life on what should be a growing number of suitable exoplanets.  We might be surprised by finding biosignature gases on planets closer to home in our own Solar System, such as phosphine on Venus, motivating new space missions for in situ exploration.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

OCTOBER 29, 2020
MEI-YIN CHOU
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
Host: Wenzer Qin/Sarah Geller

"Electronic Structure of Two-Dimensional Moiré Heterostructures"

It has become possible in recent years to fabricate and manipulate two-dimensional nanomaterials in the laboratory that are as thin as one to few atomic layers. The reduced dimensionality gives rise to unique physical and chemical properties that differ from those of traditional bulk materials. Computational studies have played a central role in understanding and predicting these novel properties. In this talk, I will focus on the moiré patterns in van der Waals heterostructures that will modify the local band gap, interlayer interaction, and structural parameters, and induce intriguing physical properities.

Time: 12:00 pm *NOTE SPECIAL TIME
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

NOVEMBER 5, 2020
MARI CARMEN BAÑULS
Max-Planck-Institute of Quantum Optics
Host: William Detmold

"Tensor Networks for numerical studies of quantum many-body dynamics"

The term Tensor Network States (TNS) designates a number of ansatzes that can efficiently represent certain states of quantum many-body systems. In one spatial dimension, the paradigmatic example is the family of Matrix Product States (MPS), extremely powerful to study ground states, low energy excitations, and thermal equilibrium states. Quantum information theory provides tools to understand why TNS are good ansatzes for physically relevant states, and some of the limitations connected to the simulation algorithms. Most significantly, while to some extent TNS can be used to study real time evolution, a full description of the most general out-of-equilibrium setup is often out of reach.  

In this talk I will present the basic ideas behind TNS algorithms, as well as the limitations and some alternative approaches that try to push their application for dynamical problems. 

Time: 12:00 pm *NOTE SPECIAL TIME
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

NOVEMBER 12, 2020
CHANDRALEKHA SINGH
University of Pittsburgh
Host: Edmund Bertschinger

"Facilitating thinking and learning in and beyond the physics classrooms"

I will discuss, using my research in physics education, how research can be used as a guide to develop curricula and pedagogies to reduce student difficulties and for making physics equitable and inclusive. My research has focused on improving student understanding of introductory and advanced concepts, for example, in learning quantum mechanics.  We are developing research-validated learning tools such as tutorials and peer instruction tools that actively engage students in the learning process.  I will first discuss how we evaluate the effectiveness of these tools using a variety of methodologies. I will then describe our research studies that provide guidelines for how to enhance physics by making it inclusive. I will discuss how a field-tested short intervention was implemented at the beginning of a physics course and how it improved the performance of underrepresented students in introductory physics classes compared to the comparison group.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

NOVEMBER 19, 2020
NATALIA TORO
Stanford University
Host: Philip Harris

"Shining New Lights on Dark Matter"

Dark matter is as mysterious as it is ubiquitous.  Cosmological evidence raises more questions than it answers about the origin and nature of the most abundant kind of matter in the Universe.  Terrestrial experiments searching for answers have focused mainly on the possibility that the constituent of dark matter is a new particle near the Higgs boson mass scale — at the upper limit of the energy ranges ever explored in the laboratory.  Recent years have seen a growing interest in lighter dark matter candidates  with constituents between the electron and proton mass scales, and even lighter.   These are "hidden under our noses" both figuratively (unseen despite their well-explored energy range) and literally (they imply that there's at least one undetected dark matter particle in your nose right now).  Using the measured abundance of dark matter as a guiding clue, I will explore the possibilities for such light dark matter, and some of the ways that small laboratory and accelerator experiments can test them.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

DECEMBER 3, 2020
PETER ONYISI
University of Texas, Austin
Host: Philip Harris

"Top Quarks: The New Flavor"

"The Large Hadron Collider has provided an enormous dataset of proton-proton collisions at the highest energies ever achieved in a laboratory.

With our new ability to study the Higgs boson and the unprecedentedly large sample of top quarks, a new frontier has opened: the flavor physics of the top quark - at heart, the question of how the top quark interacts with the Higgs field. We can start to ask questions such as whether the Higgs field is the unique source of the top quark's mass and whether there are unexpected interactions between the top quark and the Higgs boson. The answers to these will shed light on what may lie beyond the particle physics Standard Model and have cosmological implications. "

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

DECEMBER 10, 2020
NADAR ENGHETA
University of Pennsylvania
Host: Marin Soljačić

"Structuring Light with Spatiotemporal Metamaterials"

Materials are often used to manipulate waves and fields. Metamaterials have provided far-reaching possibilities in achieving “extremes” in such wave-matter interaction. Various exciting functionalities have been achieved in exploiting metamaterials and metasurfaces in nanophotonics and nano-optics. We have been exploring how spatiotemporal metamaterials can give us new platforms in structuring light for exploiting waves to do certain useful functions for us. Several scenarios are being investigated in my group. As one scenario, we have been developing metastructure platforms that can perform analog computation, such as solving integral and differential equations and inverting matrices, with waves as waves interact with them. Such “metamaterial machines” can function as wave-based analog computing machines, suitable for micro- and nanoscale integration. Another scenario deals with 4-dimensional (4D) metamaterials, in which temporal variation of material parameters is added to the tools of spatial inhomogeneities for manipulating light-matter interaction with spatiotemporal platforms. These 4D structures can also be used for manipulation of diffusion to achieve asymmetric diffusion and trapping. The third category of structured waves is achieved in the near-zero-index materials and associated photonic doping that exhibit unique features in light-matter interaction, opening doors to exciting new wave-based and quantum optical features. In this talk, I will present some of our ongoing work in the above topics, and will forecast possible future research directions in these paradigms.

Time: 4:00 pm
Virtual link: Email Ryan Higgins <higginsr@mit.edu>

Last updated on December 1, 2020 3:59 PM