Events on Thursday, February 6th, 2025
- R. G. Herb Condensed Matter Seminar
- Probing and controlling 2D magnets through the lens of quantum sensors
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Brian Zhou, Boston College
- Abstract: Recently, the single electron spin of a defect in diamond known as the nitrogen-vacancy (NV) center has emerged as a versatile nanoscale magnetometer capable of operation in extreme environments and at diverse interfaces. In this seminar, I will highlight my group’s efforts to leverage NV quantum sensing for the high resolution imaging and detection of dynamical magnetization responses in 2D layered magnetic materials, which are difficult to probe by alternative techniques. We introduce novel quantum-enabled protocols to measure the ac magnetic susceptibility and optically-induced magnetization dynamics in atomically thin magnets. Moreover, we demonstrate the switching and detection of antiphase even-layer states in a 2D A-type antiferromagnet. This control over antiferromagnetic domains enables multilevel exchange bias on connected ferromagnetic-like regions through lateral exchange coupling. NV quantum sensors thus open a unique lens for understanding and controlling 2D magnetism for spintronic technologies.
- Host: Tiancheng Song
- Atomic Physics Seminar
- 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
- Astronomy Colloquium
- Inside NASA Communication: Incredible Science, Excruciating Suspense, SMH SNAFU’s and the Challenge of Communicating it All
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Dr. Michelle Thaller, NASA
- Abstract: I have been involved in communication for everything from our Mars missions to Climate measurements to JWST. How do you talk about the search for life without attracting tabloid headlines (I failed at that one)? What can you do to get the public excited about a very focused experiment that is yielding astonishing but obscure results? We’ll look at some amazing science results -hopefully some that you’ve never heard of before, and take a look behind the scenes of NASA science communication.
- Host: Melinda Soares-Furtado
