Events

Non-equilibrium dynamics of dissipative strongly-correlated quantum matter

Tue, 23 Jun 2026 10:28:41 +0000

Thursday, 25th of June, 2026 from 9 a.m. to 11 a.m.

Sala P3 (Piso 1 do Pavilhão de Matemática) do IST/Online

Understanding relaxation in interacting quantum many-body systems is a central problem in modern physics. While isolated systems thermalize through internal quantum chaos, realistic systems are inevitably coupled to external environments, giving rise to open-system dynamics where dissipation and memory effects can strongly modify relaxation processes. This thesis investigates relaxation in open quantum many-body systems in both Markovian and non-Markovian regimes.

In the first part, we formulate and test a Lindbladian analogue of the eigenstate thermalization hypothesis (ETH), characterizing the statistical structure of observables in the eigenbasis of generic Liouvillian superoperators. Using numerical simulations of several chaotic models, we demonstrate the universality and robustness of this Lindbladian ETH ansatz, including in regimes where trace preservation is relaxed.

In the second part, we study a strongly correlated open Sachdev-Ye-Kitaev (SYK) model coupled to pseudogapped non-Markovian baths. Using the Keldysh formalism and large-N methods, we uncover a rich dynamical phase diagram featuring bath-driven …

Adaptive Pseudospectral Evolutions of Wave Models on Hyperboloidal Slices

Tue, 23 Jun 2026 10:53:19 +0000

Thursday, 25th of June, 2026 from 9 a.m. to 11 a.m.

Sala V1.25 (Piso 1 do Pavilhão de Civil) do IST/Online

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This thesis extends the bamps framework to solve the wave equation on both hyperboloidal slices and hyperboloidal layers. We demonstrate that the implemented methods achieve promising convergence results in both settings. We further investigate how our code handles the inclusion of perturbations in our initial conditions for the hyperboloidal layers setup, again obtaining encouraging numerical results.

Building on this framework, we study the cubic wave equation, exploring both decaying and blowup solutions through numerical simulations. By tuning initial data toward the threshold of blowup, we obtain solutions approaching critical behavior within the limitations of our numerical implementation. In addition, we provide numerical support for several results from modern partial differential equations theory by computing the blowup rate of numerically generated blowup solutions and evaluating the associated power indices across the computational domain for decaying solutions.

As part of this work, we also developed the foundation of an analysis software suite …

Microstructured Grayscale Optics with Direct Laser Writing for Structured Light

Tue, 23 Jun 2026 10:42:39 +0000

Thursday, 25th of June, 2026 from 10 a.m. to noon

Sala V1.01 (Piso 1 do Pavilhão de Civil) do IST

This thesis develops a platform for the fabrication of diffractive optical elements in fused silica for structured light generation in high-energy ultrafast regimes. For this purpose, a direct laser writing grayscale lithography process, followed by inductively coupled plasma reactive ion etching transfer into fused silica, was established. Different blazed diffractive axicons were fabricated to be used in ultrafast two-dimensional spectroscopy (27 μm- period), synthetic motion experiments (27 μm- period), and light spring (spatio-temporal beams) generation for laser-plasma interaction (9 and 12 μm- period), the latter using a narrowband 1030 nm laser.

The fabrication process optimization included the AZ 1518 photoresist dose-height curve calibration, the selection of the development time, and the use of a temporary thermoplastic adhesive layer during etch transfer, to limit photoresist thermal degradation. The axicons were characterized by profilometry, scanning electron microscopy, and first-order diffraction efficiency measurements.

The axicons with a period of 27 μm achieved efficiencies …

Intensity-Tunable All-Glass Kerr Meta-Optics

Wed, 24 Jun 2026 09:34:09 +0000

Friday, 26th of June, 2026 from 11 a.m. to 1 p.m.

Sala P3 (Piso 1 do Pavilhão de Matemática) do IST

This thesis investigates intensity-tunable all-glass metaoptics based on the Kerr nonlinear response of fused silica. Phase-sensitive characterization methods were developed, combining modal decomposition for structured beams with ultrafast off-axis digital holography. Low-energy measurements of structured-light metasurfaces validated the platform and methodology for high-energy experiments.

The intensity-dependent response of fused-silica nanopillars was studied using FDTD simulations, which predicted only a small Kerr-induced phase shift before the expected damage threshold. Simulations with implanted gold nanoparticles predicted a five-orders-of-magnitude increase of the nonlinear response, while revealing critical simulation limitations. This motivated a high-energy two-dimensional experimental phase library as a function of nanopillar size and incident intensity. The measured response was larger than predicted and dependent on sample orientation, indicating additional contributions beyond the nanopillar Kerr response.

Measurements showed increasing thermal contributions with repetition rate at high intensity. The critical rate for thermal accumulation was predicted as 1.8 Hz, consistent with single-shot measurements following …