TY - JOUR T1 - Observation of bound state self-interaction in a nano-eV atom collider JF - Nature Communications Y1 - 2018 A1 - Ryan Thomas A1 - Matthew Chilcott A1 - Eite Tiesinga A1 - Amita B. Deb A1 - Niels Kjærgaard AB -

Quantum mechanical scattering resonances for colliding particles occur when a continuum scattering state couples to a discrete bound state between them. The coupling also causes the bound state to interact with itself via the continuum and leads to a shift in the bound state energy, but, lacking knowledge of the bare bound state energy, measuring this self-energy via the resonance position has remained elusive. Here, we report on the direct observation of self-interaction by using a nano-eV atom collider to track the position of a magnetically-tunable Feshbach resonance through a parameter space spanned by energy and magnetic field. Our system of potassium and rubidium atoms displays a strongly non-monotonic resonance trajectory with an exceptionally large self-interaction energy arising from an interplay between the Feshbach bound state and a different, virtual bound state at a fixed energy near threshold.

VL - 9 UR - https://arxiv.org/abs/1807.01174 CP - 4895 U5 - https://doi.org/10.1038/s41467-018-07375-8 ER -