Karen Wintersperger

PhD Student

Ludwig-Maximilians-Universität München

Schellingstr. 4

80799 München

k.wintersperger[at]physik.uni-muenchen.de

What fascinates me about my work is the great degree of control we have over the experimental parameters enabling the direct measurement of abstract theoretical concepts.

Description

I am doing my PhD at LMU in the group of Immanuel Bloch. We are investigating ultracold atoms in an optical honeycomb lattice to simulate new phases of matter which are otherwise difficult to observe in conventional solid state systems.

Publications

Parametric Instabilities of Interacting Bosons in Periodically Driven 1D Optical Lattices

K. Wintersperger, M. Bukov, J. Näger, S. Lellouch, E. Demler, U. Schneider, I. Bloch, N. Goldman, and M. Aidelsburger

Physical Review X 10, 011030 (2020).

Show Abstract

Periodically driven quantum systems are currently explored in view of realizing novel many-body phases of matter. This approach is particularly promising in gases of ultracold atoms, where sophisticated shaking protocols can be realized and interparticle interactions are well controlled. The combination of interactions and time-periodic driving, however, often leads to uncontrollable heating and instabilities, potentially preventing practical applications of Floquet engineering in large many-body quantum systems. In this work, we experimentally identify the existence of parametric instabilities in weakly interacting Bose-Einstein condensates in strongly driven optical lattices through momentum-resolved measurements, in line with theoretical predictions. Parametric instabilities can trigger the destruction of weakly interacting Bose-Einstein condensates through the rapid growth of collective excitations, in particular in systems with weak harmonic confinement transverse to the lattice axis. Understanding the onset of parametric instabilities in driven quantum matter is crucial for determining optimal conditions for the engineering of modulation-induced many-body systems.

10.1103/PhysRevX.10.011030

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