Non-equilibrium quantum dynamics and formation of the Bose polaron

• Published in: Nature physics Vol. 17; no. 6; pp. 731 - 735
• Main Authors: Skou, Magnus G., Skov, Thomas G., Jørgensen, Nils B., Nielsen, Kristian K., Camacho-Guardian, Arturo, Pohl, Thomas, Bruun, Georg M., Arlt, Jan J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-06-2021; Nature Publishing Group
• Subjects: 639/766/119/2791; 639/766/36; 639/766/36/1125; 639/766/483/3926; Atomic; Bose-Einstein condensates; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Dynamics; Elementary excitations; Equilibrium; Evolution; Impurities; Interferometry; Letter; Mathematical and Computational Physics; Molecular; Optical and Plasma Physics; Physics; Physics and Astronomy; Polarons; Quantum phenomena; Theoretical
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/s41567-021-01184-5

Advancing our understanding of non-equilibrium phenomena in quantum many-body systems remains one of the greatest challenges in physics. Here we report on the experimental observation of a paradigmatic many-body problem, namely the non-equilibrium dynamics of a quantum impurity immersed in a bosonic environment
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,
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. We use an interferometric technique to prepare coherent superposition states of atoms in a Bose–Einstein condensate with a small impurity-state component, and monitor the evolution of such quantum superpositions into polaronic quasiparticles. These results offer a systematic picture of polaron formation
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–
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from weak to strong impurity interactions. They reveal three distinct regimes of evolution with dynamical transitions that provide a link between few-body processes and many-body dynamics. Our measurements reveal universal dynamical behaviour in interacting many-body systems and demonstrate new pathways to study non-equilibrium quantum phenomena.
Quantum impurities immersed in a bosonic environment can evolve into polaronic quasiparticles, so-called polarons. Interferometric measurement reveals this transition, which involves three different regimes dominated by few-body and many-body dynamics.