Ultracold and Ultrafast: Manipulating quantum gases with femtosecond laser pulses

DIPC Seminars

Philipp Wessels, University of Hamburg, Germany
Donostia International Physics Center
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Ultracold and Ultrafast: Manipulating quantum gases with femtosecond laser pulses Bridging the worlds of ultrafast physics and ultracold quantum matter opens up new pathways to manipulate macroscopic wave functions on femtosecond time- scales and to control the formation of ions and electrons in a quantum gas via strong-field ionization for the creation of new hybrid quantum systems. The combination of both expertise allows a precise measurement of absolute strong-field ionization probabilities by using well-defined atomic targets with negligible kinetic energy. In the demanding regime where the Keldysh parameter is close to unity, we find remarkable agreement with ab-initio theory obtained in collaboration with DIPC [1]. By forming many ions and electrons in a micrometer-sized region, an ultracold plasma emerges where the charged-particle dynamics substantially cools the electrons within picoseconds. This provides access to strongly coupled plasma far from equilibrium and finds applications in electron sources with a high degree of spatial coherence. Additionally, the femtosecond laser pulse allows imprinting a phase onto the macroscopic wave function of a Bose-Einstein condensate on ultrafast time scales. This leads to well controlled expanding or contracting quantum fluids with enormous peak accelerations up to 10^10 m/s². [1] P. Wessels, B. Ruff, T. Kroker, A. K. Kazansky, N. M. Kabachnik, K. Sengstock, M. Drescher, and J. Simonet, "Absolute strong-field ionization probabilities of ultracold rubidium atoms", Commun. Phys. 1, 32 (2018).