Events at Physics
Events on Thursday, April 19th, 2018
- Atomic Physics Seminar
- Ultracold Polyatomic Molecules via Laser Cooling – N Atoms Too Many
- Time: 2:00 pm
- Place: 5310 Chamberlin
- Speaker: Prof. John Doyle , Harvard
- Abstract: Triatomic molecules are deceptively simple. Even though there is only one additional atom compared to a diatomic molecule, this leads to non-trivial additional motional degrees of freedom and new associated quantum numbers. This, plus the larger density of states, realizes a quantum object whose complexity leads to new chemistry and physics research opportunities and concomitantly presents new challenges in molecular control. The science opportunities include the development of accurate and precise manipulation of chemical reactions and collisions in a qualitatively more complex species. But the reach of triatomics also includes dramatically improved, novel approaches to searches for physics beyond the Standard Model, and enhanced platforms for quantum computing using molecular tweezer arrays, both of which are aided by the low lying bending modes present in triatomic molecules. All of these research frontiers with triatomics, and their symmetric and asymmetric top brethren, either require or are greatly enhanced by chilling them to ultracold temperatures where they can be prepared in exquisitely well-defined internal and external motional states.
The recent experimental advances in direct laser cooling of diatomic molecules and triatomic molecules clearly indicates that full extension of laser tools - the creation of a magneto-optical trap (MOT) plus sub-Doppler cooling - to triatomic species should be possible. Recently in our laboratory we achieved a magneto-optical trap of diatomic molecules with CaF, sub-Doppler cooling to 40 µK, and loading of these molecules into an optical dipole trap. We also accomplished the first laser cooling and bichromatic force deflection of a polyatomic molecule, using SrOH. In addition, in 2016 we proposed the laser cooling of more complex polyatomic molecules using the methods we have now demonstrated. In particular, symmetric top molecules like CaOCH3 (and, possibly, related asymmetric top molecules) look extremely promising for direct laser cooling. The experimental prospects for a MOT of CaOH, YbOH, and CaOCH3 will be discussed.
- Host: Saffman
- Astronomy Colloquium
- "The Atomic to Molecular (HI-to-H2) Transition in Galaxy Star-Forming Regions"
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall, Cookies and Coffee 3:30 PM, Talk begins at 4:00 PM
- Speaker: Dr. Amiel Sternberg, Tel Aviv University, Max Planck Inst. for Extraterrestrial Physics, Germany, Flatiron Institute, Simons Foundation USA
- Abstract: The atomic to molecular hydrogen (HI-to-H2) phase transition is of fundamental importance for star-formation and the emergence of chemical complexity in the interstellar medium of galaxies. I will present an overview, and discuss recent theoretical studies, numerical and analytic, of the HI-to-H2 transition in irradiated systems, with applications to the multi-scale behavior observed in star-forming galaxy disks from low- to high-redshift.