Collective Excitations of Dilute Bose-Fermi Superfluid Mixtures

Valtan, Bernhard Hikaru; Nishida, Munehiro; Kurihara, Susumu

Collective Excitations of Dilute Bose-Fermi Superfluid Mixtures

Authors

Valtan, Bernhard Hikaru

Nishida, Munehiro

Kurihara, Susumu

Description

Using the effective action formalism, we investigate collective excitations of a dilute mixture of a Bose gas and a two component Fermi gas when both bosons and fermions have undergone superfluid transitions. We show that there is a repulsion between Bogoliubov and Anderson modes, which has important implications including disappearance of boson superfluidity. We derive an analytic expression for the long-wavelength dispersion relation of the mixture at zero temperature and give a condition for the instability. We also numerically calculate the damping rate due to boson-fermion interaction at finite temperatures and show that the two modes are stable at sufficiently low temperatures.
5 pages,3 figures