Georg M. Bruun

TL;DR: Radio frequency spectroscopy of ultracold bosonic ^{39}K atoms is used to experimentally demonstrate the existence of a well-defined quasiparticle state of an impurity interacting with a BEC, and finds excellent agreement with theories that incorporate three-body correlations, both in the weak-coupling limits and across unitarity.

TL;DR: In this paper, the authors used radio-frequency spectroscopy to identify a long-lived, metastable quasiparticle in a lithium-potassium Fermi mixture with strongly repulsive interactions.

TL;DR: In this article, the Fermi polaron problem is applied to the study of itinerant ferromagnetism, a long-standing problem in quantum mechanics, and it is shown that the polaron problems can be used to model the phase diagram of strongly interacting population-imbalanced quantum mixtures.

TL;DR: It is shown that the polaron problem can be applied to the study of itinerant ferromagnetism, a long-standing problem in quantum mechanics.

TL;DR: Radio-frequency spectroscopy is used to measure the complete excitation spectrum of fermionic 40K impurities resonantly interacting with a Fermi sea of 6Li atoms, and shows that a well-defined quasiparticle exists for strongly repulsive interactions, and finds that when the effective range is of the order of the interparticle spacing, there is a substantial increase in the lifetime of the quAsiparticles.