We experimentally demonstrate control of molecular rotation in bulk superfluid 4He. Metastable helium dimers, He2∗, are rotationally excited by a periodic train of linearly polarized femtosecond laser pulses. We show that the degree of rotational excitation of He2∗ can be enhanced or suppressed by varying the period of the pulse train, whereas the directionality of molecular rotation can be controlled by the relative angle between the polarization vectors of pulses in the train. The experimental results are in agreement with numerical calculations, based on a simple model, in which He2∗ molecules do not interact with the superfluid.
@article{arxiv.2311.13077,
title = {Coherent control of molecular rotation in superfluid helium},
author = {Alexander A. Milner and Ian MacPhail-Bartley and Katarina Preocanin and Shroyon Dasgupta and Xuanshan Peng and Valery Milner},
journal= {arXiv preprint arXiv:2311.13077},
year = {2023}
}