Expansion of a quantum degenerate boson-fermion mixture

TL;DR

This paper investigates how boson-fermion interactions influence the expansion dynamics of an ultracold quantum mixture, revealing the importance of relative radial motion and trapping frequencies, supported by numerical simulations aligned with experimental data.

Contribution

It provides a detailed analysis of the role of boson-fermion interactions on expansion dynamics, highlighting the impact of radial frequency ratios, with numerical results matching experimental observations.

Findings

Interaction affects the aspect ratio evolution during expansion

Radial frequency ratio crucially influences dynamics

Numerical simulations agree with experimental data

Abstract

We study the expansion of an ultracold boson-fermion mixture released from an elongated magnetic trap, in the context of a recent experiment at LENS (G. Roati et al., Phys. Rev. Lett. 89, 150403 (2002)). We discuss in some details the role of the boson-fermion interaction on the evolution of the radial-to-axial aspect ratio of the condensate, and show that it depends crucially on the relative dynamics of the condensate and degenerate Fermi gas in the radial direction, which is characterized by the ratio between the trapping frequency for fermions and for bosons. Our numerical simulations are in reasonable agreement with the experiment.