Laser controls molecular rotation in superfluid helium
Freiburg, 23/01/2026
Together with colleagues from the University of British Columbia, Frank Stienkemeier has shown that molecules can be rotated precisely in superfluidhelium. The method delivers new findings on the properties of superfluid.
Together with his colleagues from Canada, Frank Stienkemeier used a novel optical centrifuge to investigate the properties of microscopic superfluid. Photo: Sandra Meyndt / University of Freiburg
An experimental study with the participation of Professor Dr Frank Stienkemeier from the Institute of Physics at the University of Freiburg shows that the rotation of individual molecules in superfluid helium nanodroplets can be controlled precisely. Led by Prof. Valery Milner from the University of British Columbia, Canada, the team used an innovative optical centrifuge to stimulate molecules with a laser pulse over a continuous frequency range and track their dynamics over time.
This technology has already been used to study molecules in gases, however its use for the study of superfluid, in which frictionless movement is possible, is new. The method that was used applies a brief time-delay between the laser pulses, causing interferences to arise, which produce a controlled, low rotation speed and thus allow the rotatability of the molecules to be characterised. “Our findings bring us a step closer to decoding the properties of microscopic superfluid and the use of nanodroplets as objects for precision measurements at a molecular level,” says Stienkemeier. The study appeared in the academic journal Physical Review Letters on 22 January.
Further information
- Original publication: MacPhail-Bartley, Ian; Milner, Alexander A.; Stienkemeier, Frank; Milner, Valery (2026): Control of Molecular Rotation in Helium Nanodroplets with an Optical Centrifuge. Physical Review Letters
- DOI: doi.org/10.1103/5jnj-97vs