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Observation of bound state self-interaction in a nano-eV atom collider



R Thomas, M. Chilcott, A. Deb, Eite Tiesinga, N. Kjaergaard


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 res- onance 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 below threshold.
Nature Communications


laser cooled atom, ultracold collisions, collisional resonances


Thomas, R. , Chilcott, M. , Deb, A. , Tiesinga, E. and Kjaergaard, N. (2018), Observation of bound state self-interaction in a nano-eV atom collider, Nature Communications, [online],, (Accessed April 15, 2024)
Created November 19, 2018, Updated October 12, 2021