Density Modulations of Zero Sound

TL;DR

This paper investigates how a moving impurity induces density modulations in an interacting Fermi gas at zero temperature, highlighting the role of zero sound modes and the influence of interaction potential characteristics.

Contribution

It provides a semi-analytic assessment of zero sound contributions to density oscillations and explores how these effects depend on interaction potential features.

Findings

Zero sound propagates density modulations above a certain impurity speed.

Zero sound contribution varies significantly with interaction potential strength, range, and shape.

Density oscillations are distinguished from incoherent particle-hole excitations.

Abstract

We study the density modulation of an interacting Fermi gas caused by the uniform motion of an impurity at zero temperature. For strong enough interaction among Fermi atoms, the modulation propagates thanks to the excitation of the collective zero sound mode if the impurity speed is above the zero sound threshold. We are able to assess, via a semi-analytic evaluation, the extent of the zero sound contribution to the density oscillation over and above the incoherent background of particle-hole excitations. Given the strong dependence of the results on the features of the gas interaction potential, we also analyze how they vary depending on its strength, range and shape.