Quantum Science Seminar #61

Non-perturbative (cavity) QED

January 13, 2022
Peter Rabl - TU Wien (Vienna - Austria)

The structure of atoms, molecules and solids is mainly determined by static Coulomb forces, while the coupling to the quantized degrees of freedom of the electromagnetic field plays only a secondary role. Recently, it has been speculated that this general rule can be overcome in the context of cavity quantum electrodynamics (QED), where the coupling of dipoles to a single field mode can exceed the bare energy of the photon itself. Under these conditions, light-matter interactions become non-perturbative, as characterized by an effective finestructure constant of order unity. In this seminar I will give a basic introduction to this extreme coupling regime of cavity QED and explain how vacuum-induced many-body effects can lead to novel ground state phases in QED, which are the opposite of what has been assumed so far. Beyond a purely fundamental interest, these general mechanisms can be important for potential applications, ranging from cavity-assisted chemistry to quantum technologies based on ultrastrongly coupled circuit QED systems.


[1] P. Forn-Díaz, L. Lamata, E. Rico, J. Kono, and E. Solano

"Ultrastrong coupling regimes of light-matter interaction"

Reviews of Modern Physics 91, 025005 (2019)

[2] Daniele De Bernardis, Philipp Pilar, Tuomas Jaako, Simone De Liberato, and Peter Rabl

"Breakdown of gauge invariance in ultrastrong-coupling cavity QED"

Physical Review A 98, 053819 (2018)

[3] Michael Schuler, Daniele De Bernardis, Andreas M. Läuchli, and Peter Rabl

"The vacua of dipolar cavity quantum electrodynamics"

SciPost Physics 9, 066 (2020)

Access the live talk at 17.00 CEST or the recording afterwards via this link:

Quantum Science Seminar #61 - Peter Rabl

Here you can find the recording of the last lecture by Christine Silberhorn

Quantum Science Seminar #60 - Christine Silberhorn

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