Non-adiabatic QED

Driving electrons by atomically strong optical fields, non-perturbative dynamics such as the generation of high harmonic or high-order sideband radiation can arise, allowing for a detailed insight into the carrier dynamics, switching spins and building quasiparticle accelerators. In a complementary limit, electrons can be dressed solely by vacuum field fluctuations in microcavities, which results in the formation of new light-matter hybridized eigenstates – the foundation of cavity quantum electrodynamics.

In our group we push the limit of light-matter interaction to the ultrastrong and deepstrong coupling regime, where light and matter exchange energy faster than their fundamental oscillation period. Here anti-resonant interactions govern the dynamics, giving rise to a modified vacuum ground state and novel quantum effects. By reaching coupling strengths of unprecedented levels, we even get a nonzero population of vacuum photons in the ground state. In our group we have pioneered ultrafast control and custom-tailoring of this exciting regime, exploring nonlinear dynamics and more quantum phenomena of ultra- and deepstrong light-matter coupling.

Selection of breakthrough publications

We stripped electrons free of their photon dress on a subcycle timescale

M. Halbhuber et al., Nature Photonics 14, 675 (2020)

We broke the normal-mode approximation of ultrastrong coupling

J. Mornhinweg et al., Phys. Rev. Lett., 126, 177404 (2021)

We switched on coupling on a subcycle scale

G. Günter et al., Nature, 458, 178-181 (2009)

We reached a new record coupling strength

A. Bayer et al., Nano Letters 17, 6340 (2017)

We custom-tailored the dynamics of intersubband polaritons

J. Raab et al., Nature Communications 11, 4290 (2020)

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