Zero sound is the name given by Landau to the unique quantum vibrations in quantum Fermi liquids.
This sound can no longer be thought of as a simple wave of compression and rarefaction.
As the shape of Fermi distribution function changes slightly(or largely), zero sound propagates in the direction for the head of Fermi surface with no change of the density of the liquid.
References
Piers Coleman, "introduction to many body physics"
Retrieved from "http://en.wikipedia.org/"
All text is available under the terms of the GNU Free Documentation License
