The Sounds of Quantum Fermi Fluids
Ordinary classical fluids have a single type of sound waves consisting of longitudinal compressional oscillations of the density. Solids, on the other hand, have also transverse or shear sound waves because of their non-zero restoring force to shear deformations. In this talk, I will illustrate that quantum fermi liquids can radically deviate from this paradigm by developing a sharp collective transverse or shear sound wave when their interactions increase beyond a threshold, even though their ground state remains in a liquid state without any form of proper static crystalline order. I...