title: Bose Polarons in the Strongly Interacting Regime.
abstract: When an impurity is immersed in a Bose-Einstein condensate, impurity-boson interactions are expected to dress the impurity into a quasiparticle, the Bose polaron. We superimpose an ultracold atomic gas of ^{87}Rb with a much lower density gas of fermionic ^{40}K impurities. Through the use of a Feshbach resonance and radio-frequency spectroscopy, we characterize the energy, spectral width, and lifetime of the resultant polaron on both the attractive and the repulsive branches in the strongly interacting regime. The width of the polaron in the attractive branch is narrow compared to its binding energy, even as the two-body scattering length diverges.
authors: JILA, NIST, and University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
authors: Ming-Guang
authors: MG
authors: Hu
authors: JILA, NIST, and University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
authors: Michael J
authors: MJ
authors: Van de Graaff
authors: JILA, NIST, and University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
authors: Dhruv
authors: D
authors: Kedar
authors: JILA, NIST, and University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
authors: John P
authors: JP
authors: Corson
authors: JILA, NIST, and University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
authors: Eric A
authors: EA
authors: Cornell
authors: JILA, NIST, and University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
authors: Deborah S
authors: DS
authors: Jin