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Jeudi 17 octobre 2019 - 10:30 ¡¡ attention, créneau inhabituel !!

Modes sonores dans des liquides quantiques unidimensionnels

Konstantin Matveev (Argonne, États-Unis)

par Revaz Ramazashvili - 17 octobre 2019

I will discuss sound in one-dimensional Galilean invariant quantum liquids. In contrast to classical fluids, instead of a single sound mode in a broad range of frequencies the system supports two sound modes. The nature of these modes depends on the type of particles forming the quantum liquid. In systems of spin-1/2 fermions, these are the first and second sound modes propagating at two different speeds. Similarly to superfluid helium, the first sound is a wave of density, whereas the second one is a wave of entropy. On the other hand, in spinless quantum liquids the two sound modes have a hybrid nature : they are simultaneous oscillations of both density and entropy. Their speeds are nearly equal, with the difference scaling linearly with the temperature.

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