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Thursday, 05 Oct. 2023

Video-Recording for any system with MP4-support

- Video.mp4 (ca. 409 Mb)

15:15 – 16:15

“Static and dynamic properties of helium droplets"

Prof. Dorte Blume

(Oklahoma State University)

Abstract:

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.