SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 18: Nano- and Optomechanics

TT 18.5: Vortrag

Montag, 27. März 2023, 18:15–18:30, HSZ 201

Quantum friction between metals in the hydrodynamic — •Kunmin Wu, Thomas Schmidt, and Maria Belén Farias — Faculty of Science, Technology and Medicine, 162 A, avenue de la Faïencerie, L-1511 Luxembourg

In this work, we study the phenomenon of quantum friction in a system consisting on a moving atom at a constant speed parallel to a metallic slab. We use a hydrodynamic model to describe the degrees of freedom of a clean metal without internal dissipation. The moving and polarizable atom is modeled as a two-level system with a unique (l = 0) ground state and a three-fold degenerate (l = 1) excited state. We show that a quantum frictional force is present even in the absence of intrinsic damping in the metal, but that there is a velocity threshold giving rise to such a force. In particular, to have non-vanishing friction demands that the atom must move at a velocity larger than the effective speed of sound in the material. We provide analytical arguments to show that this result holds at all orders in perturbation theory. Besides, we also explore how the spatial dispersion, which is determined by the sound speed in the hydrodynamic regime, affects the friction. Our numerical results show that the spatial dispersion has less effect on the friction when the speed of atom is much higher than the sound speed.