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CCQ Institut for Fysik og Astronomi

CCQ Lunch Seminar - Jan Kumlin, University of Stuttgart: Collective Effects of Light-Matter Interactions in a Rydberg Superatom

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onsdag 29. september 2021,  kl. 11:30 - 13:00




The interaction of a single photon with an individual two-level system is the textbook example of quantum electrodynamics. Achieving strong coupling in this system has so far required confinement of the light field inside resonators or waveguides. Experiments with a Rydberg superatom [1,2] have demonstrated the ability to realize strong coupling to a propagating light pulse containing only a few photons in free space. In this talk, I present the exact input-output formalism to describe the phenomenon of collective Rabi oscillations in a single two-level Rydberg superatom coupled to a photon field. The photonic mode then defines an effective one-dimensional system, while the large size of the atomic cloud provides a chiral coupling. Extending the theory to describe several atoms coupled to a one-dimensional waveguide also provides an approach to investigate coherent internal dynamics of the atomic cloud by the exchange of virtual photons [3]. I also show how the resulting interplay between coherent exchange dynamics inside the superatom and correlated spontaneous emission from the superatom leads to nontrivial collective decay dynamics [4,5].

[1] A. Paris-Mandoki et al., Phys. Rev. X 7, 41010 (2017)

[2] N. Stiesdal et al., Phys. Rev. Lett. 121, 103601 (2018)

[3] J. Kumlin et al., Phys. Rev. Lett. 121, 013601 (2018)

[4] J. Kumlin et al., Phys. Rev. A 102, 063703 (2020)

[5] N. Stiesdal et al., Phys. Rev. Research 2, 043339 (2020)