"Theory of Particle Physics and Cosmology" Seminar

Hybrid systems of laser-cooled trapped ions and ultracold atoms combined in a single experimental setup have recently emerged as a new platform for fundamental research in quantum physics [1]. Reaching the ultracold s-wave quantum regime has been one of the most critical challenges in this field for a long time. Unfortunately, the lowest attainable temperatures in experiments using the Paul ion trap are limited by the possible rf-field-induced heating related to the micromotion [2]. Recently, buffer gas cooling of a single ion in a Paul trap to the quantum regime of ion-atom collisions was realized, and a deviation from classical Langevin theory was observed by studying the spin-exchange dynamics, indicating quantum effects in the ion-atom collisions, and next the full quantum control of ion-atom collisions with Feshbach resonances was demonstrated. In my seminar, I will present how our calculations of electronic structure and scattering dynamics guide and explain ultracold quantum physics experiments. In particular, I will describe how, in collaboration with experimental groups from Amsterdam [3] and Freiburg [4], we have overcome the micromotion limitation, reached the quantum regime, and presented quantum control of ultracold ion-atom collisions, all for the first time.[1] Tomza et al, Rev. Mod. Phys. 91, 035001 (2019)[2] Cetina et al., Phys. Rev. Lett. 109, 253201 (2012)[3] Feldker et al, Nature Phys. 16, 413 (2020)[4] Weckesser et al, soon submitted to arxiv and Nature
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