Abstract
Helium is the only element that remains liquid under normal pressure down to zero temperature. Below 2.17 K, bulk helium-4 is superfluid. Motivated by this intriguing behavior, the properties of finite-sized helium droplets have been studied extensively over the past 30 years or so. Some properties of liquid helium-4 droplets are, just as those of nuclei, well described by the liquid drop model. The existence of the extremely fragile helium dimer was proven experimentally in 1994 in diffraction grating experiments. Since then, appreciable effort has gone into creating and characterizing trimers, tetramers, and larger clusters. The excited state of the helium trimer is particularly interesting since it is an Efimov state. The existence of Efimov states, which are unique due to scale invariance and an associated limit cycle, was predicted in 1971. However, till 2015, Efimov states had-although their existence had been confirmed experimentally-not been imaged directly. Ingenious experimental advances that utilize femtosecond lasers have made it possible to directly image the static quantum mechanical density distribution of helium dimers and trimers. This talk will highlight recent experimental and theoretical work on the helium dimer, helium trimer, and helium droplets.

Bio
Doerte Blume (she/her/hers) received her PhD in physics in 1998 from the Georg-August University, Goettingen, Germany. After two and a half years of postdoctoral work at JILA/University of Colorado in Boulder, she took up a faculty position in the Department of Physics and Astronomy at Washington State University in the beautiful inland Northwest. In the summer of 2017, Doerte relocated to the Homer L. Dodge Department of Physics and Astronomy at the University of Oklahoma. Doerte is a Fellow of the American Physical Society (APS), a recipient of a Bush Lectureship at the University of Oklahoma, and a Meyer Distinguished Professorship at Washington State University. Her research accomplishments at Washington State University have been recognized through the College of Arts and Sciences Mid-Career Achievement in Scholarship/Creative Activities Award and the College of Sciences Young Faculty Performance Award. Doerte regularly co-organizes conferences of varying size, including the Conference for Undergraduate Women in Physics in 2020. In addition, she has served the scientific community as a member of the APS Division of Atomic, Molecular and Optical Physics (DAMOP) Executive Committee, Remote Associate Editor of Physical Review A, Chair of the APS Few-Body Topical Group, and member of the APS Committee on Scientific Publications.

Location:	Zoom - Facility for Rare Isotope Beams
Price:	free
Sponsor:	public
Contact:	Bob Patterer events@frib.msu.edu
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