Thomas R, Chilcott M, Tiesinga E, Deb AB, Kjærgaard N. Observation of bound state self-interaction in a nano-eV atom collider.
Nat Commun 2018;
9:4895. [PMID:
30459426 PMCID:
PMC6243998 DOI:
10.1038/s41467-018-07375-8]
[Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/25/2018] [Indexed: 12/03/2022] Open
Abstract
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.
Self-interaction of a bound state through its coupling to the continuum is a phenomenon that is very difficult to observe. Here, the authors optically collide atomic clouds of rubidium and potassium to observe the self-interaction energy through precise measurements of magnetically tunable Feshbach resonances.
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