Events

CIRCUMVENTING DEPHASING AND PUMP-DEPLETION FOR LONG AND STABLE SINGLE-STAGE PLASMA ACCELERATION: from flying-focus laser pulses to proton-bunch drivers

Wed, 20 May 2026 09:35:28 +0000

Tuesday, 9th of June, 2026 from 10 a.m. to noon

Anfiteatro PA3 (Piso -1 do Pavilhão de Matemática) do IST

Plasma wakefield acceleration offers accelerating gradients orders of magnitude beyond conventional technology. Making it widely applicable depends on finding methods to produce highquality charged-particle bunches. A critical question in this direction is how to effectively overcome pump depletion, enabling particles to be accelerated to ultra-relativistic energies in a single accelerator stage. This thesis addresses this challenge by pursuing two parallel routes to stable, single-stage acceleration.

First, we employ velocity-controlled spatio-temporal laser drivers to obtain wakefields with controllable phase velocity and apply them to the acceleration of short-lived particle beams. These shape-invariant pulses enable extended, depletion-free acceleration. We design a phase-locking scheme for decaying, sub-relativistic particles by coupling subluminal drivers with plasma density tapering.

Theoretical models and particle-in-cell simulations demonstrate the sustained acceleration of of particles orders of magnitude heavier than electrons with still maintaining high capture (reaching 100% in the optimal beam-loading regime) and preservation of transverse emittance. Another viable …

Neutrino-Induced Polarization Rotation in Astrophysical Plasmas

Wed, 03 Jun 2026 08:24:04 +0000

Tuesday, 9th of June, 2026 from 4:30 p.m. to 6 p.m.

DF Seminar Room (2-8.3), 2nd floor of Physics Building

Neutrinos are among the most abundant particles in the Universe and provide a unique probe of fundamental physics and extreme astrophysical environments. Although electrically neutral, their nonzero masses induce electromagnetic properties at loop level through Standard Model weak interactions. The dominant optical effect is parity-violating birefringence in asymmetric chiral neutrino media.

This effect rotates the polarization plane of electromagnetic radiation propagating through neutrino-permeated plasmas. In this seminar, we discuss neutrino-induced birefringence in plasmas associated with active galactic nuclei (AGN) (arXiv:2601.15910 [hep-ph]). We show that the relative bulk motion between the neutrino background and the plasma introduces a directionality factor that gives rise to an anomalous frequency dependence distinct from conventional Faraday rotation. We evaluate the effect in AGN jets, relic cosmic-neutrino backgrounds, and accretion-disk plasmas.

We also present a hyperaccretion scenario around stellar-mass black holes in which intense neutrino fluxes can significantly enhance the signal. Although the predicted rotation angles …

Quantum kinetic theory of light-matter interactions: From quantum plasmas to photon condensates

Wed, 03 Jun 2026 10:16:04 +0000

Thursday, 11th of June, 2026 from 10 a.m. to noon

Online

External link

This thesis presents a quantum kinetic description of light–matter systems in which electrons and photons are treated as fully quantum-degenerate fields. Starting from a minimal-coupling Hamiltonian, we derive coupled Wigner equations for their phase space distributions, showing how quantum light–matter interactions enter directly at the kinetic level. Taking the semiclassical limit yields modified Vlasov and fluid equations that include explicit Hartree and Fock contributions to single-particle energies, phase space velocities, and forces, together with absorption, emission, and collision terms linking the two sectors.

First, we apply the coupled kinetic equations to degenerate electron systems. In the context of quantum plasmas, the theory uncovers hybrid plasmon–photon modes and nonlinear instabilities driven by strong light–matter coupling. Extending the analysis to bilayer solid-state systems, we show that a dynamical Fock potential reshapes the phase space flow through additional shifts in plasmon dispersion and enhancement of localization effects.

Numerical solutions reveal screening and momentum …