Time-Dependent Strong Coupling Phenomena at XUV Wavelengths
Dr. Jan Marcus Dahlström
Lund University
Recent advances in free-electron laser (FEL) technology have intensified interest in coherent light-matter interactions in the extreme ultraviolet (XUV) regime. Our group is working on theoretical models for this research field in close collaboration with experimentalists, c.f. Refs. [1,2]. The high intensity attainable by FEL pulses open up for previously inaccessible phenomena, such as dressed-atom stabilization [3]. The coherent nature of seeded FEL pulses enable ultrafast control of strong coupling in atoms and ions, which results in rich dynamical absorption and fluorescence patterns [4].
In this talk, I will introduce how attosecond phase control of femtosecond XUV-FEL pulse pairs allows us to utilize “time symmetry” of pulse envelopes in strong coupling. In this way, we can then control the manifestation of entanglement in photoionization [5]. Further, I will discuss how such control can be used to reveal entanglement transfer from an electron-ion pair in photoionization, to an electron-photon pair in fluorescence [6]. Finally, we propose how similar quantum coherent control at XUV wavelengths can be used to stabilize neutral atoms in intense FEL fields. Our calculations of time-dependent dynamics in composite electron-ion-photon systems pave the way for studies of time-resolved entanglement and coherent control in more complex systems in the future.
References:
[1] Nandi, S., Olofsson, E., Bertolino, M. et al. “Observation of Rabi dynamics with a short-wavelength free-electron laser”. Nature 608, 488–493 (2022). DOI: 10.1038/s41586-022-04948-y
[2] Nandi, S., Stenquist, A., Papoulia A., et al. “Generation of entanglement using a short-wavelength seeded free-electron laser”. Sci. Adv. 10, eado0668 (2024) DOI: 10.1126/sciadv.ado0668
[3] Olofsson, E., and Dahlström, J. M. “Photoelectron signature of dressed-atom stabilization in an intense XUV field”. Phys. Rev. Research 5, 043017 (2023) DOI: 10.1103/PhysRevResearch.5.043017
[4] Stenquist, A., Zapata, F., Olofsson, E., et at. “Mollow-like triplets in ultrafast resonant absorption”. Phys. Rev. Lett. 133, 063202 (2024) DOI: 10.1103/PhysRevLett.133.063202
[5] Stenquist, A., and Dahlström, J. M. “Harnessing time symmetry to fundamentally alter entanglement in photoionization”. Phys. Rev. Research 7, 013270 (2025) DOI: 10.1103/PhysRevResearch.7.013270
[6] Stenquist, A., Bruhnke, J. N., Zapata, F., and Dahlström J. M. “Entanglement transfer in a composite electron-ion-photon system”. Rep. Prog. Phys. 88, 080502 (2025) DOI: 10.1088/1361-6633/adf354
Lund University
Recent advances in free-electron laser (FEL) technology have intensified interest in coherent light-matter interactions in the extreme ultraviolet (XUV) regime. Our group is working on theoretical models for this research field in close collaboration with experimentalists, c.f. Refs. [1,2]. The high intensity attainable by FEL pulses open up for previously inaccessible phenomena, such as dressed-atom stabilization [3]. The coherent nature of seeded FEL pulses enable ultrafast control of strong coupling in atoms and ions, which results in rich dynamical absorption and fluorescence patterns [4].
In this talk, I will introduce how attosecond phase control of femtosecond XUV-FEL pulse pairs allows us to utilize “time symmetry” of pulse envelopes in strong coupling. In this way, we can then control the manifestation of entanglement in photoionization [5]. Further, I will discuss how such control can be used to reveal entanglement transfer from an electron-ion pair in photoionization, to an electron-photon pair in fluorescence [6]. Finally, we propose how similar quantum coherent control at XUV wavelengths can be used to stabilize neutral atoms in intense FEL fields. Our calculations of time-dependent dynamics in composite electron-ion-photon systems pave the way for studies of time-resolved entanglement and coherent control in more complex systems in the future.
References:
[1] Nandi, S., Olofsson, E., Bertolino, M. et al. “Observation of Rabi dynamics with a short-wavelength free-electron laser”. Nature 608, 488–493 (2022). DOI: 10.1038/s41586-022-04948-y
[2] Nandi, S., Stenquist, A., Papoulia A., et al. “Generation of entanglement using a short-wavelength seeded free-electron laser”. Sci. Adv. 10, eado0668 (2024) DOI: 10.1126/sciadv.ado0668
[3] Olofsson, E., and Dahlström, J. M. “Photoelectron signature of dressed-atom stabilization in an intense XUV field”. Phys. Rev. Research 5, 043017 (2023) DOI: 10.1103/PhysRevResearch.5.043017
[4] Stenquist, A., Zapata, F., Olofsson, E., et at. “Mollow-like triplets in ultrafast resonant absorption”. Phys. Rev. Lett. 133, 063202 (2024) DOI: 10.1103/PhysRevLett.133.063202
[5] Stenquist, A., and Dahlström, J. M. “Harnessing time symmetry to fundamentally alter entanglement in photoionization”. Phys. Rev. Research 7, 013270 (2025) DOI: 10.1103/PhysRevResearch.7.013270
[6] Stenquist, A., Bruhnke, J. N., Zapata, F., and Dahlström J. M. “Entanglement transfer in a composite electron-ion-photon system”. Rep. Prog. Phys. 88, 080502 (2025) DOI: 10.1088/1361-6633/adf354
