Metastability in spin polarised Fermi gases and quasiparticle decays

Abstract

We investigate the metastability associated with the first order transition from normal to superfluid phases in the phase diagram of two-component polarised Fermi gases.We begin by detailing the dominant decay processes of single quasiparticles.Having determined the momentum thresholds of each process and calculated their rates, we apply this understanding to a Fermi sea of polarons by linking its metastability to the stability of individual polarons, and predicting a region of metastability for the normal partially polarised phase. In the limit of a single impurity, this region extends from the interaction strength at which a polarised phase of molecules becomes the groundstate, to the one at which the single quasiparticle groundstate changes character from polaronic to molecular. Our argument in terms of a Fermi sea of polarons naturally suggests their use as an experimental probe. We propose experiments to observe the threshold of the predicted region of metastability, the interaction strength at which the quasiparticle groundstate changes character, and the decay rate of polarons.

12 pages, 5 figures

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Cited by in corpus (5)

• Metastability and Coherence of Repulsive Polarons in a Strongly Interacting Fermi Mixture
• Strongly Correlated Quantum Fluids: Ultracold Quantum Gases, Quantum Chromodynamic Plasmas, and Holographic Duality
• Repulsive polarons and itinerant ferromagnetism in strongly polarized Fermi gases
• Excitonic states of an impurity in a Fermi gas
• Momentum-dependent quasiparticle properties of the Fermi polaron from the functional renormalization group