Events on Monday, February 3rd, 2025
- Atomic Physics Seminar
- Emergent collective phenomena in macroscopic and mesoscopic systems
- Time: 11:00 am - 12:00 pm
- Place: 5310 Chamberlin
- Speaker: Dr. Zhenjie Yan, Univ. California Berkeley
- Abstract: From the persistent electric currents in superconductors to the synchronized motion of a flock of birds, emergent collective behaviors arise ubiquitously from the interactions between constituents in many-body ensembles. Ultracold atom experiments, with their precisely tunable interactions and well-controlled initial states, provide a powerful platform to explore these cooperative phenomena in quantum many-body systems. In this talk, I will present examples of collective effects in both macroscopic and mesoscopic regimes, drawn from my recent works. First, I will discuss thermal transport in a macroscopic strongly interacting Fermi gas, a system that poses significant challenges for existing theoretical and computational methods. The heat transport reveals a striking signature of a superfluid phase transition: while heat propagates diffusively in the normal phase, it propagates as a wave—known as second sound—below the superfluid transition temperature. Next, I will introduce recent work on constructing a mesoscopic system atom-by-atom using optical tweezers, with precise control over interactions mediated by photon exchange in an optical cavity. This platform enables the study of self-organization and symmetry breaking. The atom array reveals distinctive hallmarks of mesoscopic physics, such as the dependence of the critical point and the state lifetime on the system size. Finally, I will briefly outline my future research plans to develop quantum systems that are robust against noise and decoherence using atoms and light for emulating many-body systems and carrying out computational tasks.
- Host: Mark Saffman
- Plasma Physics (Physics/ECE/NE 922) Seminar
- "Learning magnetic field structure from trajectories"
- Time: 12:00 pm - 1:15 pm
- Place: 1227 Engineering Hall
- Speaker: David Bindel, Cornell University
- Abstract: The magnetic fields in stellarators can be organized into different regions according to the dynamics of field line flows, with regions of nested flux surfaces potentially interspersed with islands or regions of chaos. While can visualize these structures with Poincare plots, such visualizations are not wholly satisfactory if we wish to numerically optimize such structures. In this talk, we describe an approach to automatically inferring the structure of magnetic field line flows by building models of the dynamics of field line trajectories with connections to dynamical systems theory, numerical extrapolation methods, and the theory of adaptive filtering.
Joint work with Max Ruth (UT Austin). - Host: Prof. Adelle Wright