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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2506.05177 |
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| _version_ | 1866908401828626432 |
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| author | Köhnke, D. Bayer, T. Wollenhaupt, M. |
| author_facet | Köhnke, D. Bayer, T. Wollenhaupt, M. |
| contents | Shaped free electron vortices (SEVs) have recently been studied using atomic (1+2) resonance-enhanced multiphoton ionization (REMPI) by oppositely chirped counterrotating circularly polarized (OC-CRCP) femtosecond laser pulses. By transitioning from the perturbative to the non-perturbative REMPI regime, we identify an adiabatic excitation mechanism in a resonant V-type three-level system, termed V-RAP due to its similarities to rapid adiabatic passage (RAP). Experimentally, we observe a pronounced change in the shape of the measured three-dimensional photoelectron momentum distribution (3D PMD), which we trace back to this mechanism via analytical calculations and numerical simulations of the bound state and ionization dynamics. In V-RAP, the atom adiabatically follows the OC-CRCP field, with the two excited states driven in anti-phase, leading to an adiabatic cancellation of specific ionization pathways and explaining the observed changes in the PMD. In the experiment, we combine supercontinuum polarization pulse shaping to generate OC-CRCP femtosecond laser pulses with velocity map imaging-based photoelectron tomography to reconstruct the 3D PMD. The reconstructed PMDs are decomposed by 3D Fourier analysis into SEVs of different rotational symmetry, revealing a significant enhancement of the $c_6$-symmetric contribution, which is the signature of the V-RAP. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_05177 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Adiabatic dynamics in a V-type quantum system by oppositely chirped counterrotating circularly polarized laser pulses Köhnke, D. Bayer, T. Wollenhaupt, M. Atomic Physics Quantum Physics Shaped free electron vortices (SEVs) have recently been studied using atomic (1+2) resonance-enhanced multiphoton ionization (REMPI) by oppositely chirped counterrotating circularly polarized (OC-CRCP) femtosecond laser pulses. By transitioning from the perturbative to the non-perturbative REMPI regime, we identify an adiabatic excitation mechanism in a resonant V-type three-level system, termed V-RAP due to its similarities to rapid adiabatic passage (RAP). Experimentally, we observe a pronounced change in the shape of the measured three-dimensional photoelectron momentum distribution (3D PMD), which we trace back to this mechanism via analytical calculations and numerical simulations of the bound state and ionization dynamics. In V-RAP, the atom adiabatically follows the OC-CRCP field, with the two excited states driven in anti-phase, leading to an adiabatic cancellation of specific ionization pathways and explaining the observed changes in the PMD. In the experiment, we combine supercontinuum polarization pulse shaping to generate OC-CRCP femtosecond laser pulses with velocity map imaging-based photoelectron tomography to reconstruct the 3D PMD. The reconstructed PMDs are decomposed by 3D Fourier analysis into SEVs of different rotational symmetry, revealing a significant enhancement of the $c_6$-symmetric contribution, which is the signature of the V-RAP. |
| title | Adiabatic dynamics in a V-type quantum system by oppositely chirped counterrotating circularly polarized laser pulses |
| topic | Atomic Physics Quantum Physics |
| url | https://arxiv.org/abs/2506.05177 |