Lemeshko Group

The angulon theory was able to describe non-adiabatic dynamics of iodine molecules in superfluid helium nanodroplets, as observed in experiments of Henrik Stapelfeldt:

B. Shepperson, A. A. Søndergaard, L. Christiansen, J. Kaczmarczyk, R. E. Zillich, M. Lemeshko,
H. Stapelfeldt
Laser-induced rotation of iodine molecules in He-nanodroplets: revivals and breaking-free,
Phys. Rev. Lett. 118, 203203 (2017)

Interestingly, the revival of alignment observed experimentally can be explained as a rotational revival of the angulon quasiparticle.

The theory was developed by Dr. Jan Kaczmarczyk, a postdoctoral fellow in our group.

Meet the ‘angulon’, a new quasiparticle found in superfluid helium

by Edwin Cartlidge

“The quasiparticle concept allows physicists to describe complex, many-body interactions in terms of the behaviour of a single particle-like entity. Usually these particles turn up in condensed-matter systems such as semiconductors, but a new type of quasiparticle known as an angulon has been proposed to describe the rotation of an atomic or molecular impurity within a solvent. First proposed theoretically two years ago, angulons have now been shown to explain the curious behaviour of a range of different molecules rotating within liquid helium. …”

See other press releases on angulons:

Phys.org, ScienceDaily, EurekAlert, Space Daily (in English),
der Standard, Austria Presse Agentur (in German)
Europapress.es (in Spanish)
Hightech.fm, Echo Moskvy (in Russian)
Kuark.org (in Turkish)
Matfyz.cz (in Czech)
Physics Bimonthly Taiwan (in Chinese)

X. Li, R. Seiringer, M. Lemeshko
Angular self-localization of impurities rotating in a bosonic bath,
Phys. Rev. A 95, 033608 (2017)

We have shown that angulons do form out of molecules rotating in superfluid helium

M. Lemeshko
Quasiparticle approach to molecules interacting with quantum solvents,
Phys. Rev. Lett. 118, 095301 (2017)

Was highlighted as a Physics Viewpoint: A new angle on quantum impurities by Yulia Shchadilova

E. Yakaboylu, M. Lemeshko
Anomalous screening of quantum impurities by a neutral environment,
Phys. Rev. Lett. 118, 085302 (2017)

Misha Lemeshko was awarded a Standalone research grant from the Austrian Science Fund (FWF) for the project “Quantum rotations in the presence of a many-body environment.” The funding will help us to develop the foundations of the angulon theory during next three years.

Congratulations to Clemens Jochum with the successful masters defense! His M.Sc. work focused on “Dissipative Few-Body Quantum Systems” (link to the .pdf file)

Our contribution to the special issue on cold molecules, “Libration of Strongly-Oriented Polar Molecules inside a Superfluid,” appeared online.

Giacomo Bighin joins our group as a postdoc. Welcome Giacomo!

Sometime ago we were invited to write a chapter on the angulons for the book “Low Energy and Low Temperature Molecular Scattering” (eds. A. Osterwalder and O. Dulieu), published by the Royal Society of Chemistry. Here comes the preprint.