Silke Ospelkaus

Silke Ospelkaus-Schwarzer is a German experimental physicist who studies ultra-cold molecular materials at the University of Hanover Institute of Quantum Optics. She was awarded a European Research Council Consolidator Award in 2022.

Ospelkaus studied physics at the University of Bonn.^[1][2] She moved to the University of Hamburg for her doctoral research, where she studied Fermi-Bose mixtures of potassium and rubidium in optical lattices.^[3][4] She was awarded the doctoral prize of the German Physical Society.^[5] She moved to the JILA and the National Institute of Standards and Technology at the University of Colorado Boulder.^[2][6][7][8]

In 2009, Ospelkaus returned to Germany, where she was made a group leader at the Max Planck Institute of Quantum Optics. She investigates the behaviour of atomic and molecular gases at ultra-cold temperatures.^[9] In particular, ultra-cold molecular gases offer hope to better understand chemical processes.^[10][5] She has investigated two species atomic quantum gases mixtures, from which she can prepare polar molecules in a degenerate state.

By cooling hot samples of sodium and potassium, Ospelkaus is able to study exotic phenomena such as hyperfine ro-vibrational electronic interactions. She first combines Zeeman slowing with two-dimensional magneto-optical trapping, and once the atoms are cooled below the Doppler limit, loads them into a magnetic quadrupole trap.^[11] At this stage, microwave evaporation cools the sodium, which results in the sympathetic cooling of potassium. At ≈ 10 μK, interactions between the sodium and magnesium become increasingly strong, and further cooling demands more sophisticated tools. These include magnetic Feshbach resonance.^[11][7]

Ospelkaus has demonstrated laser cooling to study diatomic molecules.^[10][12] She achieves this cooling using direct laser cooling and buffer gas cooling.^[13] Ultra-cold molecules are essentially stationary, which allows for their structure-property relationships to be studied at ultra-high precision. Dense gases of these molecules exhibit quantum behaviour, which allows for investigations into superconductivity.^[13]

Ospelkaus uses molecular spectroscopy to understand the quantum states of alkali metal – alkaline earth metal atomic gases.^[14] In 2022, she was awarded a European Research Council consolidator grant.^[15]

• K-K Ni; S Ospelkaus; M H G de Miranda; et al. (18 September 2008). "A high phase-space-density gas of polar molecules". Science. 322 (5899): 231–235. arXiv:0808.2963. doi:10.1126/SCIENCE.1163861. ISSN 0036-8075. PMID 18801969. Wikidata Q33370512.
• S Ospelkaus; K-K Ni; D Wang; et al. (1 February 2010). "Quantum-state controlled chemical reactions of ultracold potassium-rubidium molecules". Science. 327 (5967): 853–857. arXiv:0912.3854. doi:10.1126/SCIENCE.1184121. ISSN 0036-8075. PMID 20150499. Wikidata Q59476983.
• K-K Ni; S Ospelkaus; D Wang; et al. (1 April 2010). "Dipolar collisions of polar molecules in the quantum regime". Nature. 464 (7293): 1324–1328. arXiv:1001.2809. doi:10.1038/NATURE08953. ISSN 1476-4687. PMID 20428166. Wikidata Q59058301.