Atomic Physics Seminars |
Events During the Week of February 2nd through February 9th, 2025
Monday, February 3rd, 2025
- 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
Tuesday, February 4th, 2025
- No events scheduled
Wednesday, February 5th, 2025
- No events scheduled
Thursday, February 6th, 2025
- Adventures in optical clocks: quantum engineering, fundamental physics, and new frontiers
- Time: 11:00 am - 12:00 pm
- Place: 5310 Chamberlin
- Speaker: Dr. Tobias Bothwell, NIST Boulder
- Abstract: Optical atomic clocks are exemplary quantum sensors, combining robust environmental decoupling with exquisite laser phase sensitivity. By leveraging new quantum engineering techniques, today’s optical clocks now realize a staggering 19 digits of accuracy and precision. Beyond timekeeping, this new level of performance promises novel tests of fundamental physics, from general relativity to dark matter. Motivated by these advances, I will show how carefully controlling ensembles of neutral atoms tightly confined within optical lattices continues to push the limits of frequency metrology. I will first introduce optical lattice clocks (OLCs), which set precision records by leveraging thousands of trapped alkaline-earth-like atoms. Using strontium in a shallow lattice regime allows us to control atomic interactions and realize unprecedented measurement capability, resolving the gravitational redshift within our millimeter-scale atomic sample. In ytterbium we have developed and employed multiple ultracold ensembles within a standard OLC to measure accuracy-limiting differential atomic polarizabilities. Recently we have even operated OLCs outside the lab, with plans for measuring gravitational redshifts atop nearby mountains. Looking forward, the OLC architecture can be extended beyond alkaline-earth-like atoms, enabling a single-species clock network to explore new frontiers in both quantum metrology and fundamental physics.
- Host: Mark Saffman
Friday, February 7th, 2025
- No events scheduled
