Quasiparticle lifetime in ultracold fermionic mixtures with density and mass imbalance

Abstract

We show that atomic Fermi mixtures with density and mass imbalance exhibit a rich diversity of scaling laws for the quasiparticle decay rate beyond the quadratic energy and temperature dependence of conventional Fermi liquids. For certain densities and mass ratios, the decay rate is linear whereas in other cases it exhibits a plateau. Remarkably, this plateau extends from the deeply degenerate to the high temperature classical regime of the light species. Many of these scaling laws are analogous to what is found in very different systems including dirty metals, liquid metals, and high temperature plasmas. The Fermi mixtures can in this sense span a whole range of seemingly diverse and separate physical systems. Our results are derived in the weakly interacting limit making them quantitatively reliable. The different regimes can be detected with radio-frequency spectroscopy.

replaced with published version; title changed

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• Hetero pairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with mass imbalance
• Quasiparticle scattering rate in a strongly polarised Fermi mixture
• Thermal transitions, pseudogap behavior and BCS-BEC crossover in Fermi-Fermi mixtures
• Energy, decay rate, and effective masses for a moving polaron in a Fermi sea: Explicit results in the weakly attractive limit
• Excitonic states of an impurity in a Fermi gas
• Interplay of mass imbalance and frustration in correlated band insulators