Static and dynamic properties of helium droplets

by Prof. Doerte Blume

Thursday 5 Oct 2023, 15:15 → 16:15 Europe/Stockholm

Helium is the only element that remains liquid under normal pressure down to zero temperature. Below 2.17K, 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. In addition, pump-probe experiments yield insights into the dynamics. This talk will highlight recent theoretical work on the helium dimer, helium trimer, and small helium droplets. 
 

About the Speaker: 

 

Prof. Blume obtained her PhD in 1998 from Göttingen followed by a postdoc position in University of Colorado in Boulder. She was at the Washington State University from  2001 to 2017 and since then is a Professor at Oklahoma State University. She is also a fellow of the American Physical Society and a recipient of the Meyer Distinguished Professorship at Washington State University and the Bush Lectureship at the University of Oklahoma. Prof. Blume's research interests fall in the area of cold atom and few-body physics. Her group is particularly interested in developing a bottom-up understanding of quantum mechanical systems and their correlations in terms of a few key parameters.