Optics Seminar
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2026-01-15 (Thursday)
room 0.06, Pasteura 5 at 10:15 
Szymon Pustelny (Jagiellonian University)Non-Hermitian Dynamics and Exceptional-Point Sensing in a Hybrid Spin System
Incorporating non-Hermitian dynamics into quantum systems leads to a range of intriguing phenomena, including non-reciprocity, parity–time symmetry breaking, and the emergence of exceptional points, at which two or more eigenstates coalesce. These features can result in enhanced sensitivity to weak perturbations, offering a distinct approach to quantum sensing.During the talk, I will discuss the emergence of exceptional points in a hybrid system composed of two distinct gases—rubidium vapor and a noble gas—and demonstrate how this framework enhances sensitivity to magnetic fields. I will also show how such a system can be employed to search for non-magnetic interactions.
2026-01-08 (Thursday)
room 0.06, Pasteura 5 at 10:15
Krzysztof Jachymski (Faculty of Physics, University of Warsaw)Stone skipping with ions in degenerate quantum gases
The dynamics of a charged impurity immersed in a quantum medium can be quite complex due to the long-range nature of the interactions. The ion can excite the gas during its motion, changing momentum in a nonlinear way. I will describe the simplest theoretical approaches to this problem based on the transformation to the co-moving frame. Dressing the impurity with the host atoms can result in formation of a polaronic state characterized by effective mass, which may be detectable in state-of-the art experiments. I will also report on recent experimental efforts aiming to understand three-body recombination involving an ion, which is competing with many-body effects.