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Enrico Perfetto (University of Rome Tor Vergata)4/21/26, 9:00 AM
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Massimo Ferrario4/21/26, 9:15 AM
The EuPRAXIA@SPARC_LAB facility is the beam-driven pillar of the
EuPRAXIA project, which aims to establish by the end of 2031 the first
European Research Infrastructure dedicated to plasma-based accelerators.
The facility is expected to demonstrate the usability of such
accelerators to deliver high-brightness electron beams in the 1–5 GeV
range for a broad user community.One of the...
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Prof. Stefano Lupi (Department of Physics and INFN, Sapienza University of Rome)4/21/26, 9:45 AM
The emergence of complex phases in quantum materials—ranging from unconventional superconductivity to topologically protected states is governed by a delicate balance of competing interactions that define their unique low-energy excitations. These excitations are, in most cases, resonant with Terahertz (THz) and Infrared (IR) radiation, making these spectral ranges the ideal playground for...
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28. Theoretical Modeling of Ultrafast Phase Transitions from the Femtosecond to the Picosecond ScaleMatteo Calandra Buonaura (Università di Trento)4/21/26, 10:15 AM
In this talk, I will introduce a theoretical approach [1,2] to ultrafast phase transitions that captures both electron/hole and phonon dynamics following laser pumping, on time scales ranging from a few femtoseconds to hundreds of picoseconds after the action of the pulse.
At short times, the method relies on solving the manybody Bloch equations coupled to Ehrenfrest dynamics in the space...
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Francesco Stellato (University of Rome Tor Vergata & INFN)4/21/26, 11:30 AM
Plasma-based accelerators are enabling a new generation of compact ultrafast photon sources for probing matter on femtosecond time scales. EuPRAXIA is a European initiative aimed at developing compact plasma-based accelerators for next-generation light sources and advanced scientific applications. The infrastructure will be implemented at two sites: one at the ELI Beamlines facility,...
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Myrta Gruening (Queen’s University Belfast)4/21/26, 12:00 PM
Understanding and controlling nonlinear photocurrents in low‑dimensional materials is key to advancing optoelectronics. In this work, we present a first‑principles real‑time framework to compute the shift‑current response (a second-order bulk photovoltaic effect) and apply it to two‑dimensional Janus transition‑metal dichalcogenides (TMDs). Our approach accurately incorporates excitonic...
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Michael Schüler (Paul Scherrer Institute / University of Fribourg)4/21/26, 12:30 PM
Accurately modeling the transition from initial Bloch states to final photoelectron states is essential for bridging the gap between intrinsic material properties and experimentally observed intensities in angle-resolved photoemission spectroscopy (ARPES). This is particularly critical for time-resolved studies (trARPES), where the interplay of experimental geometry and many-body dynamics can...
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Stefania Pagliara (Università Cattolica del Sacro Cuore)4/21/26, 2:45 PM
Ultrafast photoexcitation of layered semiconductors leads to the formation of stable excitonic features, making these systems an ideal platform for investigating excitonic many-body interactions and their coupling to lattice and spin degrees of freedom on ultrafast timescales. The goal of this talk is to present experimental protocols based on ultrafast optical and photoemission spectroscopies...
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Alejandro Molina Sanchez (Universidad de Valencia)4/21/26, 3:15 PM
Excitons in van der Waals materials exhibit remarkable properties arising from reduced dimensionality, strong Coulomb interactions, and tunable dielectric environments. In this talk, I will discuss recent advances in understanding ultrafast exciton dynamics in these systems, combining state-of-the-art experiments and many-body theoretical simulations. Time-resolved spectroscopies reveal a rich...
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Daniel Santos Stone (CNRS, TIMES, AMU)4/21/26, 4:30 PM
Pump-probe experiments are essential for probing the nonequilibrium optical properties of 2D materials, providing direct, time-resolved access to exciton formation and thermalization dynamics.
Until very recently, methods for ab initio real-time excitonic dynamics were limited to a coherent-incoherent regime separation, where the Bloch equation/TD-DFT and Boltzmann/RT-BSE formalisms were...
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Carlos Betancur (PhD student, University of Rome Tor Vergata)4/21/26, 4:45 PM
This work compares two first-principles frameworks for describing the ultrafast dynamics of photoexcited carriers in semiconductors: the excitonic Bloch equations (XBE), which capture the coupled evolution of coherent, incoherent, and irreducible excitons, and the semiconductor electron–phonon equations (SEPE), derived from the ab initio Kadanoff–Baym formalism and formulated in terms of...
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Petru Milev (Istituto di Struttura della Materia-CNR (ISM-CNR))4/21/26, 5:00 PM
Understanding the optical response of quantum materials is essential for the development of next-generation photonic and optoelectronic devices. We employ a many-body perturbation theory approach for the study of excited states and optical properties, building on recent methodological advances that have significantly expanded the capabilities for modeling light–matter interactions in complex...
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Gianluca Stefanucci (dipartimento di fisica, universita' di roma tor vergata)4/22/26, 9:15 AM
We present a first-principles formulation of the excitonic Bloch equations
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to track, in real time, the populations of coherent, irreducible, and incoherent excitons during and after optical excitation. We then develop a unified framework that links the dynamics of coherent and incoherent excitons to distinct, experimentally accessible excitonic sidebands. Our central result is a practical... -
Antonio Picón (Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC))4/22/26, 9:45 AM
We present a numerical study demonstrating that topological phase transitions can be identified through an attosecond absorption spectroscopy scheme. Focusing on a Chern insulator whose topological character is tuned via second order hopping, we simulate the out of equilibrium electron dynamics driven by a circularly polarized infrared pump and probed by an ultrafast attosecond x ray pulse....
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maurizia palummo (Tor Vergata University)4/22/26, 10:15 AM
The development of next-generation optoelectronic technologies relies on the identification and detailed understanding of new materials with tailored properties. First-principles simulations of ground and excited states provide a powerful approach to reveal the microscopic mechanisms governing their behavior and to deliver predictive guidance for experimental research.
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In this presentation,... -
Prof. Lara Benfatto (Department of Physics, Sapienza University of Rome)4/22/26, 11:30 AM
Light-induce breaking of time-reversal symmetry in insulating crystals is usually interpreted in terms of the so-called Inverse Faraday Effect (IFE), i.e. the magnetization of media by circularly-polarized light. Early attempts to measure it showed that the strengths of both the direct Faraday effect -i.e. the rotation of the electric-field polarization in the presence of a static applied...
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Fulvio Paleari (CNR - Nanoscience Institute)4/22/26, 12:00 PM
Low-dimensional layered materials, hosting strongly bound excitons, are highly relevant for optoelectronic applications and constitute an ideal platform for the investigation of nonequilibrium exciton dynamics. In particular, in transition metal dichalcogenide (hetero)bilayers, the landscape of electronic excitations may be engineered either by controlling (i) the spatial localization of...
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Prof. Mariana Rossi (MPI for the Structure and Dynamics of Matter)4/22/26, 12:30 PM
In this talk, I will discuss recent progress in performing atomistic simulations of solids, liquids and molecules driven by light. I will show examples where light drives nuclear motion and phase transitions by primarily to nuclear degrees of freedom [1], as well as situations where the relaxation of electronic excitations is dramatically changed by nuclear dynamics [2]. These examples are...
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Matteo Lucchini (Dipartimento di Fisica - Politecnico di Milano)4/22/26, 2:45 PM
Doping is a fundamental element of semiconductor technology, providing a powerful means to tailor electronic properties and underpinning modern microelectronics. As device dimensions continue to shrink toward their fundamental limits, new approaches for ultrafast information processing are required. One promising direction is the use of intense, ultrashort laser pulses to control electronic...
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Claudio Attaccalite (CNRS/Aix-Marseille Université CINaM)4/22/26, 3:15 PM
In this talk, I will discuss the shift current response in two-dimensional systems. In particular, I will focus on three possibilities: 1) increasing the shift current response by modifying the density of states in twisted materials; 2) using external perturbations, such as magnetic fields, to engineer shift current response; 3) the strong electron-hole interaction in low-dimensional systems....
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Victor Garcia (Christian-Albrechts-Universität zu Kiel)4/22/26, 4:15 PM
Polaron formation in pump-probe experiments is a fast, non-equilibrium process arising from the coupled motion of electrons and lattice vibrations, leading to the emergence of a localized quasiparticle. A new first-principles quantum-kinetic approach is introduced to track the real-time dynamics of electrons and the lattice under electron-phonon interactions. We applied this method to the...
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Torsten Geirsson (University of Valencia)4/22/26, 4:30 PM
The magnetoelectric (ME) effect provides a promising pathway for controlling magnetic functionalities using electric fields. While first-principles approaches to the static linear ME response have been rigorously developed and successfully benchmarked, comparable methods for the frequency-dependent linear ME effect remain far less established, despite numerous experimental studies...
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Anna Romani (Queen's University Belfast)4/22/26, 4:45 PM
The non-equilibrium optical properties of Transition Metal Dichalcogenides (TMDs) are deeply influenced by the interaction between electronic excitations and lattice vibrations. Real-time propagation methods within the Bethe-Salpeter Equation (BSE) or Independent Particle Approximation (IPA) frameworks often rely on a phenomenological constant damping as the dissipation channel to stabilize...
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Subhojit Pal (Università degli Studi di Palermo, Dipartimento di Fisica e Chimica—Emilio Segrè, Via Archirafi 36, 90123 Palermo, Italy)4/22/26, 5:00 PM
The interplay between coherent electronic motion and dissipative electron-lattice interactions lies at the heart of ultrafast phenomena in quantum materials. Time- resolved spectroscopies have revealed that processes such a carrier relaxation, decoherence etc. can’t be understood from a purely unitary evolution of the electronic subsystem. Being a closed system theory, rt-TDDFT can’t describe...
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Giuseppe Ammirati (CNR-Istituto di Struttura della Materia)4/23/26, 9:15 AM
Ultrafast spectroscopy provides a unique window into photoinduced phase transitions, allowing real-time observation of the formation, evolution, and decay of correlated many-body states far from equilibrium. By resolving carrier dynamics on femtosecond timescales, these techniques can disentangle competing electronic phases and reveal the microscopic mechanisms governing collective behavior...
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Yang-hao Chan (Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan)4/23/26, 9:45 AM
Valley degree of freedom in two-dimensional transition metal dichalcogenides was proposed to be a promising quibit candidate for quantum information sciences due to the long coherence time from the coupled spin-valley physics. One of the main decoherence channel was the exchange interactions and the Maialle-Silva-Sham (MSS) type mechanism. Evidences of MSS mechanism were identified in previous...
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Daniele Varsano (CNR - Institute of Nanoscience, Italy)4/23/26, 10:15 AM
Many-body perturbation theory (MBPT), and in particular the GW approximation, provides a powerful framework to compute quasiparticle (QP) excitations and spectroscopic properties beyond density functional theory. Its application to low-dimensional systems and metals, however, is computationally challenging due to the sharp long-wavelength behavior of the screened Coulomb interaction and the...
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Phuong Mai Dinh (Laboratory for Theoretical Physique of Toulouse)4/23/26, 11:30 AM
Abstract: In a recent series of papers, we identified an unstable behavior in the electronic response of small molecules to some ultrafast XUV pulses, namely the build-up of a dipole instability at late times. Calculations have been done using real-time Time-Dependent Density Functional Theory in the Local Density Approximation version complemented by a self-interaction correction. In this...
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Riccardo Reho (University of Luxembourg)4/23/26, 12:00 PM
Understanding and modelling light–matter interaction through spectroscopic techniques is crucial for the development of next-generation technologies, including optoelectronics, quantum devices, and energy conversion [1]. In this context, we investigate the optical properties of two-dimensional materials where reduced screening and strong many-body effects enhance excitonic phenomena.
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In this... -
Umberto De Giovannini (University of Palermo)4/23/26, 12:30 PM
Time-dependent density functional theory (TDDFT) provides a powerful framework to describe electron dynamics in real time, but its standard formulation is inherently unitary and therefore unable to capture dissipative processes that are essential in solids. In this talk, I present recent developments toward a first-principles description of ultrafast dynamics that combines real-time TDDFT with...
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Stefano Dal Conte (Politecnico di Milano)4/23/26, 2:45 PM
Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted significant attention due to their distinctive optical and electronic properties. These include strong light–matter interactions, tightly bound excitons, excitonic Rydberg states, multiparticle excitonic complexes, many-body effects, and chiral valley-selective optical responses. Such features have enabled the...
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Dr Davide Sangalli (Istituto di Struttura della Materia (ISM) - CNR)4/23/26, 3:15 PM
I will present recent numerical and theoretical developments, aimed at modelling nonequilibrium dynamics in advanced materials from first-principles, and to capture the generation and dynamics of coherent excitons within the TD-HSEX scheme.
In the first part, I will discuss coherent exciton dynamics in the atto-second regime in LiF, an insulator with the largest known band gap, and hosting...
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Hannah Bertschi (Max Planck Institute for the Structure and Dynamics of Matter)4/23/26, 4:15 PM
Understanding how large-amplitude anharmonic nuclear motion influences electronic excitations is essential for explaining related phenomena in weakly-bound systems. To model charge transfer and vibronic spectra, we employ real-time time-dependent density functional theory coupled to multitrajectory Ehrenfest dynamics. In this approach, nuclear anharmonicity is incorporated through the sampling...
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Karina Madela Landivar Zambrana (Phd student-Università degli Studi di Milano)4/23/26, 4:30 PM
Over the last decades, two-dimensional (2D) materials have gained significant attention as promising platforms for next-generation quantum technologies [1]. Defect engineering in 2D materials enables control of phenomena relevant for spintronics and quantum information processing [2,3] thanks to their tunable electronic, optical, and mechanical properties. For example, low-energy ion...
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Lifeng Ou (University of Valencia)4/23/26, 4:45 PM
Atomically thin transition metal dichalcogenides semiconductor emerges as promising candidates for novel optoelectronic application, displaying weak dielectric screening due to its truly two-dimension character. The optical properties are mostly related to inter-band transitions between valence and conduction bands, also called the strongly binding electron-hole pair, exciton. Strain is...
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Ms Tingting GU (Laboratoire de Physique Théorique de Toulouse, Université de Toulouse, Université Paul Sabatier,)4/23/26, 5:00 PM
The interaction of finite electronic systems, such as Na₉⁺ clusters, with intense ultrafast laser pulses induces complex electronic dynamics, including ionization and multi-electron excitations. While standard TDDFT captures the laser-driven single-particle dynamics, it is limited in describing electron–electron correlations. To overcome this, we employ the Stochastic Time-Dependent Local...
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Elena Stellino (Sapienza Università di Roma)4/24/26, 9:15 AM
Exciton physics represents a core field in the research on 2D materials from both a fundamental and an application- oriented perspective. In this context, recent years have seen growing interest in understanding the mechanisms governing the conversion of neutral excitons into charged excitons (trions), a process that marks a transition from an optoelectronic response based on bosonic...
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Andrea Marini (CNR-ISM)4/24/26, 9:45 AM
The time--resolved angle--resolved photoemitton spectra of WSe$_2$, a
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paradigmatic metal dichalcogenide, is dominated by a peak that,
initially observed withing the gap at the $K$ valley, scatters, on an
ultra--fast time scale of $\sim 30$ fs to the S valley.
In this work we question the commonly used interpreation of the
experimental observations in terms of a massive bound... -
Luca Perfetti (Ecole Polytechnique)4/24/26, 10:15 AM
Excitons underpin the operation of optoelectronic devices by governing light–matter interactions in semiconductors. Conventionally, these bound electron–hole quasiparticles are expected to destabilize at high photoexcitation densities owing to screening-induced weakening of the Coulomb interaction. Recent theoretical work, however, has challenged this paradigm by predicting that resonant...
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Giovanni Marini4/24/26, 11:30 AM
Ultrafast light pulses provide a unique and powerful handle to control quantum materials far from equilibrium, enabling access to phases and functionalities that are fundamentally inaccessible under thermal conditions. Acting on femtosecond timescales, photoexcitation can selectively perturb electronic, lattice, and spin degrees of freedom, rapidly reshaping the free-energy landscape to access...
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Muralidhar Nalabothula (University of Luxembourg)4/24/26, 12:00 PM
Excitons play a central role in mediating light matter interactions in two dimensional materials and wide bandgap insulators such as hexagonal boron nitride. While robust ab initio methods like the Bethe Salpeter Equation (BSE) are widely used to compute excitonic energies and wave functions, the symmetry properties of excitons in crystals and their associated selection rules have received...
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Enrico Perfetto (University of Rome Tor Vergata)4/24/26, 12:30 PM
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Wanzhu He (University of Palermo)
The investigation of topology and topological phase transitions has emerged as a cornerstone in modern condensed matter physics, offering profound implications for the development of fault-tolerant quantum information technologies. A central challenge in this field lies in identifying robust experimental signatures that can unambiguously characterize the topological nature of electronic...
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