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arXiv · 2503.24038

Giant counter-rotating oscillations on the attosecond timescale

Jakob Nicolai Bruhnke·Edvin Olofsson·Axel Stenquist·Jan Marcus Dahlström
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Abstract

We predict an unexplored type of ultrastrong coupling between atoms and intense ultraviolet light that leads to giant population oscillations on the attosecond timescale. These counter-rotating oscillations can be of similar amplitude as the elementary femtosecond Rabi oscillations between the two strongly coupled states. The effect, which is beyond the two-level atom, is non-reciprocal: It only affects the excited state, while the ground state is unaffected. We propose that two-photon Rabi oscillations (1s$^2$-1s3d) in helium is suitable for the generation of this type of ultrastrong coupling with realistic pulses. We use a combination of Floquet theory and effective Hamiltonian theory to test our predictions against ab initio simulations.

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Jakob Nicolai Bruhnke, Edvin Olofsson, Axel Stenquist, Jan Marcus Dahlström. 2025-03-31. Giant counter-rotating oscillations on the attosecond timescale. https://arxiv.org/abs/2503.24038

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