Towards Engineering Ultrafast Quantum Light–Matter Dynamics at the Nanoscale

Ultrafast control of light–matter interactions at the nanoscale provides a route to manipulate optical, electronic, and quantum degrees of freedom before dissipation dominates. This talk presents an integrated perspective on three complementary research directions that collectively illustrate how nanoscale geometry, ultrafast optical driving, and resonant electromagnetic modes can be leveraged to manipulate energy flow and electronic dynamics with high temporal precision in the context of recent advances in ultrafast plasmonics [1] and hybrid polaritonic systems [5].   First, I will show how femtosecond transient gratings can act as reconfigurable photonic structures [2]. By optically writing a transient permittivity modulation in a dielectric layer coupled to a hyperbolic metamaterial, it becomes possible to supply the missing momentum required to excite Bloch plasmon polaritons in otherwise unpatterned multilayers [2]. This approach opens a pathway to dynamic control of high-momentum, deeply confined modes and to quantum-optical environments for emitters, nanoscale light routing, and ultrafast polariton manipulation [2,5].   Second, I will discuss strong light–matter interactions in plasmonic molecular systems [5]. Pump–probe experiments reveal that molecular polaritons formed in photoswitch–nanoantenna platforms can collapse to localized molecular excitations within a few hundred femtoseconds [3]. This provides direct insight into how coherent hybrid states evolve, lose polaritonic character, and reshape molecular energy landscapes on chemically relevant timescales, with implications for polaritonic chemistry, quantum nanophotonics, and ultrafast molecular control [3,5].   Third, I will show how nanoscale porosity modifies electronic temperatures, interband thresholds, and the balance between intraband and interband excitations, thereby broadening hot-carrier generation and altering relaxation pathways [4]. This illustrates how morphology can be used to tune carrier dynamics, optical response, and device-relevant functionality, for instance in photocatalysis [4].   These studies feature how spatial, spectral, and temporal degrees of freedom can be engineered and dynamically intertwined at the nanoscale, to eventually gain access to regimes where optical fields steer matter before dissipation sets in - paving the way for next‑generation photonic circuitry, real‑time control of chemical reactivity, efficient hot‑carrier devices, programmable metamaterials and quantum-optical interfaces.     References   [1] A. N. Koya, M. Romanelli, J. Kuttruff, N. Henriksson, A. Stefancu, G. Grinblat, A. De Andres, F. Schnur, M. Vanzan, M. Marsili, M. Rahaman, A. V. Rodríguez, T. Tapani, H. Lin, B. D. Dana, J. Lin, G. Barbillon, R. P. Zaccaria, D. Brida, D. Jariwala, L. Veisz, E. Cortés, S. Corni, D. Garoli, and N. Maccaferri, Appl. Phys. Rev. 10, 021318 (2023).   [2] T. Tapani, H. Kempf, M. Pancaldi, L. Foglia, E. Pedersoli, R. Totani, A. Valerio, R. Mincigrucci, I. Nikolov, M. B. Danailov, A. De Andrés, R. Krahne, P. Vavassori, F. Bencivenga, F. Capotondi, D. Garoli, and N. Maccaferri, arXiv:2605.20513 (2026).   [3] J. Kuttruff, M. Romanelli, E. Pedrueza-Villalmanzo, J. Allerbeck, J. Fregoni, V. Saavedra-Becerril, J. Andréasson, D. Brida, A. Dmitriev, S. Corni, and N. Maccaferri, Nat. Commun. 14, 3875 (2023).   [4] T. Tapani, J. M. Pettersson, N. Henriksson, C. M. Brunner, A. C. Zimmermann, E. Zäll, N. V. Hauff, L. Das, A. Sapunova, G. Balestra, M. Cuscunà, A. De Andrés, T. Giovannini, D. Garoli, and N. Maccaferri, Nat. Commun. 17, 829 (2026).   [5] B. Johns, A. Schirato, F. Toffoletti, T. Giovannini, M. Vanzan, M. Marsili, G. Parolin, G. Dall’Osto, A. K. Poonia, C. Cappelli, F. Baletto, S. Corni, E. Collini, M. Maiuri, and N. Maccaferri, arXiv:2605.01583 (2026).