Critical velocity and dissipation mechanism in finite superfluid 4He nanodroplets
Abstract
A hallmark of superfluidity is the frictionless motion of an object below the Landau critical velocity; Whether this concept applies to nanoscale droplets remains unclear. Using time-dependent density functional theory, we investigate the motion of a sodium atom on the surface and inside a superfluid helium nanodroplet. For surface motion, we identify a critical velocity above which energy dissipation through ripplon excitation and the formation of surface-bound quantized vortices leads to rapid deceleration. Inside the droplet, the atom is slowed down to a steady-state velocity that depends on the initial speed, contrasting experiments reporting a critical velocity for dopants ejected from droplets [Phys. Rev. Lett. 111, 153002 (2013)]. Remarkably, the velocity of the ejected atom is nearly independent of its initial velocity. We demonstrate that this behavior results from the bursting of the bubble surrounding the atom at the droplet surface, challenging the previous experimental interpretation.
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BibTeX
@misc{sishodia2026critical,
title = {{Critical velocity and dissipation mechanism in finite superfluid $^4$He nanodroplets}},
author = {Keshav Sishodia and Ernesto García-Alfonso and Nadine Halberstadt and Sivarama Krishnan and Marcel Mudrich},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.35728},
eprint = {2610.35728},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.35728},
}
RIS
TY - UNPB
TI - Critical velocity and dissipation mechanism in finite superfluid ^4He nanodroplets
AU - Keshav Sishodia
AU - Ernesto García-Alfonso
AU - Nadine Halberstadt
AU - Sivarama Krishnan
AU - Marcel Mudrich
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.35728
UR - https://arxiv.org/abs/2610.35728
AB - A hallmark of superfluidity is the frictionless motion of an object below the Landau critical velocity; Whether this concept applies to nanoscale droplets remains unclear. Using time-dependent density functional theory, we investigate the motion of a sodium atom on the surface and inside a superfluid helium nanodroplet. For surface motion, we identify a critical velocity above which energy dissipation through ripplon excitation and the formation of surface-bound quantized vortices leads to rapid deceleration. Inside the droplet, the atom is slowed down to a steady-state velocity that depends on the initial speed, contrasting experiments reporting a critical velocity for dopants ejected from droplets [Phys. Rev. Lett. 111, 153002 (2013)]. Remarkably, the velocity of the ejected atom is nearly independent of its initial velocity. We demonstrate that this behavior results from the bursting of the bubble surrounding the atom at the droplet surface, challenging the previous experimental interpretation.
ER -