Time: 1pm AEST (3pm NZST)

Speaker: Professor Niels Kjaergaard
Affiliation: University of Otago, New Zealand


The resonance is arguably the most striking phenomenon in scattering physics. Near a resonant energy, the number of particles scattered may either be dramatically enhanced or suppressed. In this talk I will explore what happens when two resonance features are simultaneously in play. Using a laser based collider for ultracold atoms, we establish a pristine scenario where the separation of two bare scattering resonance can be tuned via an external magnetic field. Upon bringing the resonances close together, coupling leads to an avoided crossing akin to that observed in a closed two level quantum system. For our open system of colliding atoms, the avoided crossing happens in a complex-valued energy space, where the participating resonances can be ascribed to poles of the so-called S-matrix for the system. The flow of such S-matrix poles ensuing from tuning an interaction potential has been discussed for more than 70 years, but has awaited an observation in a collision experiments as most potentials are easier to tune in a computer code than in real life.


About Australia - New Zealand Cold Atom Seminars

This new initiative hosts a seminar once a month for the Australia – New Zealand cold atom research community.  The purpose is to encourage and facilitate ongoing discussions and collaboration in the local community.  Talks should be less than 40 minutes in length to allow ample time for questions and discussion.

Seminars will be held on the last Friday of the month (except for December) at 1pm Melbourne time (which is normally 3pm New Zealand time).  While the primary format is online via Zoom, various institutions will host the seminar in local seminar rooms.  The Zoom link is https://uqz.zoom.us/j/88604569495

You can sign up for announcements for the seminars at this webpage:

Seminars are recorded, and past seminars can be accessed from this web page.

Contact Matthew Davis mdavis@physics.uq.edu.au for further information.



Priestley Building (67)
442 (or via Zoom address https://uqz.zoom.us/j/88604569495)