Polaron to molecule transition in a strongly imbalanced Fermi gas

Understand

A single down spin Fermion with an attractive, zero range interaction with a Fermi sea of up-spin Fermions forms a polaronic quasiparticle.

• The associated quasiparticle weight vanishes beyond a critical strength of the attractive interaction, where a many-body bound state is formed.
• From a variational wavefunction in the molecular limit, we determine the critical value for the polaron to molecule transition.
• The value agrees well with the diagrammatic Monte Carlo results of Prokof'ev and Svistunov and is consistent with recent rf-spectroscopy measurements of the quasiparticle weight by Schirotzek et.