TITLE: Attosecond non-linear dynamics in molecules: correlation, coherences and entanglement

AUTHOR: Alicia Palacios, Departamento de Química & Instituto de Física de la Materia Condensada (IFIMAC), Universidad Autónoma de Madrid

DAY OF THE TALK: September, 17 - 12PM

WHERE: Sala de Seminarios, ICMM-CSIC

ABSTRACT: 

Attosecond science has rapidly transitioned from observing and tracking the fundamental electronic motion in atoms to actively manipulating correlated electron-nuclear dynamics in increasingly complex systems. This talk presents recent theoretical advances describing ultrafast non-linear phenomena driven by Free-Electron Lasers (FELs) and High-Order Harmonic Generation (HHG) techniques [1-4]. Exploiting the unprecedented optical phase control of seeded FELs like FERMI, we recently explored the potential of using a self-referencing harmonic comb approach to isolate the photoionization phases, crucially identifying measurement-induced continuum-continuum phases that break down long-standing asymptotic approximations, in order to access the time delays in the photoelectron emission, in the attosecond time scales [1,2]. We further explored the use of alternative two-color (w/2w) XUV schemes to measure these photoionization time delays, revealing novel modulations driven by molecular vibrational timescales [5]. These new experimental techniques come to complement standard attosecond spectroscopic techniques such as RABBITT or attosecond electron streaking. Transitioning to HHG pulse synthesis, we explore quantum entanglement as a novel control parameter. By tracking entanglement between the photoelectron and parent ion with phase-locked attosecond pulses, we demonstrate how tuning inter-pulse delays can actively preserve or erase the electronic coherence required for charge migration [6]. Finally, the talk will outline ongoing methodological progress in scaling these grid-based methods to larger systems via on-the-fly molecular dynamics, paving the way for steering chemical reactivity at the attosecond limit.

References:

[1] Maroju et al., Nature 578 386 (2020) & Comm. Phys. 8 207 (2025)

[2] Rajendran et al. (arXiv:2603.15293)

[3] Prince et al., Nature Photonics 10 176 (2016)

[4] You, D. et al. Phys. Rev. X 10, 031070 (2020)

[5] Holzmeier et al. (arXiv:2604.05666)

[6] Koll, Suñer, Witting, Bello, Palacios, Martín and Vrakking, Nature 652, 82 (2026)