| 2. | G. Inzani, V. Eggers, M. Meierhofer, L. Münster, J. Helml, R. Wallauer, S. Zajusch, S. Ito, L. Machtl, H. Yin, C. Kumpf, F. C. Bocquet, C. Bao, J. Güdde, F. S. Tautz, R. Huber, U. Höfer Direct subcycle momentum-resolved observation of Landau-Zener-Majorana transitions in lightwave-driven graphene Conference vol. 14077, 2026. @conference{Inzani2026,
title = {Direct subcycle momentum-resolved observation of Landau-Zener-Majorana transitions in lightwave-driven graphene},
author = {G. Inzani and V. Eggers and M. Meierhofer and L. Münster and J. Helml and R. Wallauer and S. Zajusch and S. Ito and L. Machtl and H. Yin and C. Kumpf and F. C. Bocquet and C. Bao and J. Güdde and F. S. Tautz and R. Huber and U. Höfer},
url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/14077/3099485/Direct-subcycle-momentum-resolved-observation-of-Landau-Zener-Majorana-transitions/10.1117/12.3099485.full},
doi = {10.1117/12.3099485},
year = {2026},
date = {2026-05-26},
volume = {14077},
abstract = {Understanding electron motion driven by the carrier field of light is central to the development of lightwave electronics. In this work, we directly observe field-driven Landau-Zener-Majorana transitions in graphene with sub-cycle band-structure videography. Our experimental approach combines photoemission momentum microscopy with strong phase-stable few-cycle mid-infrared pump pulses and ultrashort extreme-ultraviolet probe pulses, enabling field-resolved measurements of carrier dynamics throughout the entire Brillouin zone. Time-resolved measurements around a Dirac point of graphene reveal the evolution of the electron distribution during the optical cycle: carriers accelerate away from the Fermi level and are displaced along the Dirac cone. This creates an asymmetric occupation which generates an ultrafast current. The transient two-dimensional carrier distribution encodes the signature of Landau-Zener-Majorana transitions and uncovers electron-electron and electron-phonon scattering pathways. Access to the full two-dimensional momentum space with subcycle resolution provides key insights into the physical phenomena dictating coherent light–matter interaction. This methodology opens new opportunities for exploring strong-field phenomena in solids, including inter- and intraband dynamics, Bloch oscillations, and Floquet-Bloch states. },
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Understanding electron motion driven by the carrier field of light is central to the development of lightwave electronics. In this work, we directly observe field-driven Landau-Zener-Majorana transitions in graphene with sub-cycle band-structure videography. Our experimental approach combines photoemission momentum microscopy with strong phase-stable few-cycle mid-infrared pump pulses and ultrashort extreme-ultraviolet probe pulses, enabling field-resolved measurements of carrier dynamics throughout the entire Brillouin zone. Time-resolved measurements around a Dirac point of graphene reveal the evolution of the electron distribution during the optical cycle: carriers accelerate away from the Fermi level and are displaced along the Dirac cone. This creates an asymmetric occupation which generates an ultrafast current. The transient two-dimensional carrier distribution encodes the signature of Landau-Zener-Majorana transitions and uncovers electron-electron and electron-phonon scattering pathways. Access to the full two-dimensional momentum space with subcycle resolution provides key insights into the physical phenomena dictating coherent light–matter interaction. This methodology opens new opportunities for exploring strong-field phenomena in solids, including inter- and intraband dynamics, Bloch oscillations, and Floquet-Bloch states. |
| 1. | V. Eggers, G. Inzani, M. Meierhofer, L. Münster, J. Helml, R. Wallauer, S. Zajusch, S. Ito, L. Machtl, H. Yin, C. Kumpf, F. C. Bocquet, C. Bao, J. Güdde, F. S. Tautz, R. Huber, U. Höfer Subcycle videography of lightwave-driven Landau-Zener-Majorana transitions in graphene Journal Article Forthcoming In: arXiv:2602.12844 [cond-mat.mes-hall], Forthcoming. @article{Eggers2026,
title = {Subcycle videography of lightwave-driven Landau-Zener-Majorana transitions in graphene},
author = {V. Eggers and G. Inzani and M. Meierhofer and L. Münster and J. Helml and R. Wallauer and S. Zajusch and S. Ito and L. Machtl and H. Yin and C. Kumpf and F. C. Bocquet and C. Bao and J. Güdde and F. S. Tautz and R. Huber and U. Höfer},
url = {https://arxiv.org/abs/2602.12844},
doi = {10.48550/arXiv.2602.12844},
year = {2026},
date = {2026-02-13},
journal = {arXiv:2602.12844 [cond-mat.mes-hall]},
abstract = {Strong light fields have unlocked previously unthinkable possibilities to tailor coherent electron trajectories, engineer band structures and shape emergent phases of matter all-optically. Unravelling the underlying quantum mechanisms requires a visualisation of the lightwave-driven electron motion directly in the band structure. While photoelectron momentum microscopy has imaged optically excited electrons averaged over many cycles of light, actual subcycle band-structure videography has been limited to small electron momenta. Yet lightwave-driven elementary processes in quantum materials often occur throughout momentum space. Here, we introduce attosecond-precision, subcycle band-structure videography covering the entire first Brillouin zone (BZ) and visualize one of the most fundamental but notoriously elusive strong-field processes: non-adiabatic Landau-Zener-Majorana (LZM) tunnelling. The interplay of field-driven acceleration within the Dirac-like band structure of graphene and periodic LZM interband tunnelling manifest in a coherent displacement and distortion of the momentum distribution at the BZ edge. The extremely non-thermal electron distributions also allow us to disentangle competing scattering processes and assess their impact on coherent electronic control through electron redistribution and thermalization. Our panoramic view of strong-field-driven electron motion in quantum materials lays the foundation for a microscopic understanding of some of the most discussed light-driven phenomena in condensed matter physics. },
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
Strong light fields have unlocked previously unthinkable possibilities to tailor coherent electron trajectories, engineer band structures and shape emergent phases of matter all-optically. Unravelling the underlying quantum mechanisms requires a visualisation of the lightwave-driven electron motion directly in the band structure. While photoelectron momentum microscopy has imaged optically excited electrons averaged over many cycles of light, actual subcycle band-structure videography has been limited to small electron momenta. Yet lightwave-driven elementary processes in quantum materials often occur throughout momentum space. Here, we introduce attosecond-precision, subcycle band-structure videography covering the entire first Brillouin zone (BZ) and visualize one of the most fundamental but notoriously elusive strong-field processes: non-adiabatic Landau-Zener-Majorana (LZM) tunnelling. The interplay of field-driven acceleration within the Dirac-like band structure of graphene and periodic LZM interband tunnelling manifest in a coherent displacement and distortion of the momentum distribution at the BZ edge. The extremely non-thermal electron distributions also allow us to disentangle competing scattering processes and assess their impact on coherent electronic control through electron redistribution and thermalization. Our panoramic view of strong-field-driven electron motion in quantum materials lays the foundation for a microscopic understanding of some of the most discussed light-driven phenomena in condensed matter physics. |
