USC Department of Physics and Astronomy

Physics and Astronomy Department Colloquium
Exploring Correlated Phases in Two-Dimensional Heterostructures
Andrew Joe
Physics and Astronomy Department
University of California, Riverside
Monday, November 24, 2025
4:15 p.m.
In-Person Location: SSL 202
Online via Zoom
Zoom ID: 979 57616028 | Passcode: 595401 | (@ USC subscribers only)
Abstract:
Since the isolation of atomically thin layers of van der Waals (vdW) materials, vdW heterostructures have been used to engineer new quantum phenomena at the two-dimensional (2D) limit. Heterostructures made of semiconducting transition metal dichalcogenide (TMD) monolayers are of particular interest because they serve as a platform that can host 2D electron gases as well as light-induced electron-hole bound pairs, known as excitons. In this talk, I will discuss how we have used these TMD heterostructures to explore correlated electronic behavior. First, I will discuss electrostatically creating interlayer excitons in MoSe2/hBN/WSe2 heterostructures. In this system, we observe the excitonic insulator phase and demonstrate perfect Coulomb drag using an optical probe. Then, I will show our recent progress on the MoSe2/WS2 heterostructure, where we observe correlated insulating states at integer fillings of the moiré lattice. The correlated insulating states persist upon switching the layer localization of the charges and can be detected using the moiré excitons in the system. Our work aims to create solid-state device platforms to explore many-body interactions of fermionic and bosonic particles, paving the way for realizing novel quantum states of matter.

Physics and Astronomy Department Colloquium
Life in a Tight Spot: Watching Bacterial Life in Complex Spaces
Sujit Datta
Division of Chemistry and Chemical Engineering
California Institute of Technology
Monday, November 10, 2025
4:15 p.m.
In-Person Location: SSL 202
Online via Zoom
Zoom ID: 979 57616028 | Passcode: 595401 | (@ USC subscribers only)
Abstract:
Bacteria in nature inhabit complex environments like mucus, biofilm matrices, and soils. However, lab studies typically focus on cells in simple liquid media or at flat interfaces. How do the material properties of these complex environments shape bacterial behavior? In this talk, I will describe my group's work addressing this question using tools from soft matter, 3D imaging, and biophysical modeling. We have developed the ability to (i) directly visualize bacteria from the scale of a single cell to that of an entire multi-cellular collective, (ii) 3D-print precisely structured collectives, and (iii) model their large-scale motion and growth in complex environments akin to natural soils and sediments. I will describe how, using this approach, we have discovered several ways in which material interactions fundamentally alter bacterial motility and growth—with implications for microbial ecology, engineered living materials, and other active matter systems.

Ever wondered ......

Should I go to grad school?
What’s it like to get a PhD?
What career paths are available?
How does funding work?
What’s the application process like?
How can I maximize my chances of getting into a good school?
What should I do now to prepare?

Come learn the answers to these questions and more!

TODAY, October 30
5:30pm
VPD 105

Physics and Astronomy Department Colloquium

Contrabass Gravitational Waves: From Nanohertz Down
Dustin Madison
Physics Department
Occidental College
Monday, November 3, 2025
4:15 p.m.
In-Person Location: SSL 202
Online via Zoom
Zoom ID: 979 57616028 | Passcode: 595401 | (@ USC subscribers only)
Abstract:
Pulsar timing array collaborations like NANOGrav (the North American Nanohertz Observatory for Gravitational Waves) have been steadily monitoring the most stable known millisecond pulsars for over twenty years. In so doing, we have begun to see in their behavior convincing evidence for a stochastic background of nanohertz gravitational waves, likely generated by a population of supermassive binary black holes. Prof. Madison will discuss how pulsar timing array experiments work, what the current state of the field is, and what the future may hold. The talk will end by discussing some ways in which even lower frequencies of gravitational waves may be probed.

Physics and Astronomy Department Colloquium
From Negligible to Neglecton: a study of symmetry in topological matter
Aaron Lauda
Department of Mathematics
USC
Monday, October , 2025
4:15 p.m.
In-Person Location: SSL 202
Online via Zoom
Zoom ID: 979 57616028 | Passcode: 595401 | (@ USC subscribers only)
Abstract:
Symmetry has long served as the organizing principle of physics, from SU(2) rotations that determine angular momentum and spin to SU(3) flavor symmetry that predicted the Ω⁻ baryon. In modern condensed-matter systems, symmetry takes on a new life in two dimensions, where the quasiparticles called anyon in topological phases obey “braid” rather than traditional bosonic or fermionic exchange statistics. We will review how these anyons provide the foundation for topological quantum computation, a fault-tolerant model in which information is stored and processed through the topology of particle worldlines rather than fragile local degrees of freedom.

In this talk, Prof. Lauda will trace how our understanding of symmetry has evolved from groups to quantum groups, and how this shift captures the physics of topological phases such as those underlying the fractional quantum Hall effect and the recently engineered topoconductors announced by Microsoft. He will then describe recent theoretical work showing that when we extend the usual framework of topological quantum field theory by allowing certain previously discarded representations to re-enter, a new type of anyon emerges. This additional excitation, the neglecton, restores a deeper layer of symmetry and leads to more powerful models of quantum computation. In particular, Ising anyons, known to be non-universal in the standard framework, become universal once these extended symmetries are included. He will close by highlighting how the evolving mathematical language of symmetry continues to shape our understanding of new phases of matter.

Bang! Goes the Universe - USC Dornsife Magazine Bang! Goes the Universe ByMargaret Crable June 18, 2025 Share Copy Link Facebook X LinkedIn Bluesky Email Almost 14 billion years ago, the universe gave birth to itself. In the manner of a glassblower shaping a molten orb, a tiny, exceptionally hot speck of dense material ballooned outward into vast...

Physics and Astronomy Department Colloquium

Chasing Dark Matter with X-Ray Instrumentation

Kerstin Perez
Department of Physics
Columbia University

Monday, March 24, 2025
4:15 p.m.
In-Person Location: SSL 202
Online via Zoom
Zoom ID: 970 4485 5262| Passcode: 523889 (@ USC subscribers only)

Abstract:
Dark matter particles could be unstable and decay, annihilate with each other, or subtly alter the processes within stellar interiors, imprinting characteristic signals in astrophysical observations. In the first part of this talk, I will review how the NuSTAR X-ray satellite telescope has delivered leading sensitivity to light dark matter candidates, in particular sterile neutrinos and axions. In the second part, I will discuss how similar focusing X-ray optics will be deployed in the International Axion Observatory (IAXO), providing leading sensitivity to axions and axion-like particles (ALPs) across a wide mass range.

Join the INTEL Open House for Chemistry and Physics students this Wednesday, March 5 in MCB 102 from 2:30-4:30pm.

Catch next week's Dornsife Dialogues to hear Profs. Di Felice and Lidar discuss Quantum Computing on Friday, Feb. 28 at 12pm. Register by clicking on the post.

Welcome! You are invited to join a webinar: The Quantum Leap: How Quantum Computing Redefines What's Possible. After registering, you will receive a confirmation email about joining the webinar. Quantum computing is set to transform how we solve some of the world's biggest problems, from accelerating medical breakthroughs to tackling climate challenges. But how does it work, and why is it so powerful? Join this live discussion with leaders in the field who will break down the basics of quan...

Physics Department Colloquium

Code CFTs: Where Generalized Symmetries, Quantum Gravity and Quantum Information Meet

Anatoly Dymarsky
University of Kentucky

Monday, November 18, 2024
4:15 p.m.
In-Person Location: SSL 202
Online via Zoom
Zoom ID: 959 3945 2450 | Passcode: 850974 (@ USC subscribers only)

Abstract:
The starting point of my story is an intriguing connection between codes (used to send information over a noisy channel) and 2d conformal field theories. While this connection is not new, until recently it had a status of a mathematical curiosity. Upon a close inspection this connection is understood to be a part of a much larger picture, where codes are proposed to be quantum and emerge from anyon condensation in some 3d topological field theory. The resulting picture gives rise to holographic duality between this 3d topological theory summed over all possible topologies and the ensemble of boundary 2d CFTs.