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Observing S-Matrix Pole Flow in Resonance Interplay

Chilcott, Matthew; Gayen, Samyajit; Croft, James; Thomas, Ryan; Kjærgaard, Niels

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Matthew Chilcott

Samyajit Gayen

Dr James Croft
Postdoctoral Research Associate

Ryan Thomas

Niels Kjærgaard


We provide an overview of experiments exploring resonances in the collision of ultracold clouds of atoms. Using a laser-based accelerator that capitalises on the energy resolution provided by the ultracold atomic setting, we unveil resonance phenomena such as Feshbach and shape resonances in their quintessential form by literally photographing the halo of outgoing scattered atoms. We exploit the tunability of magnetic Feshbach resonances to instigate an interplay between scattering resonances. By experimentally recording the scattering in a parameter space spanned by collision energy and magnetic field, we capture the imprint of the S-matrix pole flow in the complex energy plane. After revisiting experiments that place a Feshbach resonance in the proximity of a shape resonance and an anti-bound state, respectively, we discuss the possibility of using S-matrix pole interplay between two Feshbach resonances to create a bound-state-in-the-continuum.


Chilcott, M., Gayen, S., Croft, J., Thomas, R., & Kjærgaard, N. (2024). Observing S-Matrix Pole Flow in Resonance Interplay. Few-Body Systems, 65(2), Article 61.

Journal Article Type Article
Acceptance Date May 5, 2024
Online Publication Date May 25, 2024
Publication Date May 25, 2024
Deposit Date Jun 12, 2024
Publicly Available Date Jun 12, 2024
Journal Few-Body Systems
Print ISSN 0177-7963
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 65
Issue 2
Article Number 61
Public URL


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