Angle-Resolved Photoemission Spectroscopy (ARPES) is the only experimental technique that can directly image the band structure of solids, providing essential insights into their electronic, optical, and magnetic properties. When combined with ultrafast pulsed laser sources, ARPES allows us to track the dynamical evolution of these properties in real time.

At the UPHOS laboratory of the Physics Department, we employ time-resolved ARPES (tr-ARPES) to explore novel quantum materials and to uncover exotic phases of matter emerging from the complex interplay between electronic and lattice correlations, spin, and topology. Our research focuses on how light couples to the band structure and how intense optical excitation can be used to manipulate solid-state properties at the quantum level.

The goal of this Master Thesis project is to develop and characterize the generation of tunable light pulses in the near- and mid-infrared range—an essential tool to control optical excitation. The candidate will contribute to the implementation of a novel non-linear optical parametric amplifier (NOPA), followed by its experimental characterization. The candidate will then use this source to perform the first tr-ARPES experiments on Ta₂Pd₃Te₅, a promising platform for realizing an elusive quantum phase of matter: the excitonic insulator. In this exotic state, electrons and holes—normally free carriers—bind together to form excitons. When the density of these bound pairs becomes sufficiently high, they undergo a collective quantum Bose–Einstein-like condensation. The result is a completely new macroscopic quantum order, driven not by lattice vibrations as in conventional superconductors, but by the purely electronic attraction between particles. Unveiling and controlling such a phase would open a new chapter in solid-state physics, bridging the worlds of semiconductors, superconductivity, and quantum optics.

The project sits at the crossroads of the curricula in Photonic and Quantum Technologies and Quantum Materials and Nanophysics. The candidate will gain hands-on experience in non-linear optics, vacuum technology, cryogenics, and advanced optical and photoemission spectroscopies. Working with state-of-the-art equipment and within a large international collaboration, the student will take their first steps into the world of academic research.

Contacts: alberto.crepaldi@polimi.it, ettore.carpene@polimi.it, claudia.dallera@polimi.it