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Abstract:
The nonlinear interaction of zero sound with the order parameter collective modes in superfluid
3He-B is considered within perturbation theory in the amplitude of the sound field.
Selection rules for nonlinear excitation of the order parameter modes are determined by the
approximate particle‐hole symmetry of the 3He Fermi liquid. A diagrammatic algorithm,
based on the quasiclassical theory of superfluid 3He-B, is used to calculate nonlinear
coupling constants. These nonlinearities are sufficiently large that it should be possible to
observe two phonon absorption and stimulated Raman scattering of zero sound by the real
squashing (J=2+) mode. Finally, we discuss the possibility of using these
nonlinearities to produce zero sound with ‘squeezed’ noise.
Paper: [PDF]
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