Promotionsvortrag Physik: Insights into physical states of loop quantum gravity using techniques from machine learning

Ankündigung des Promotionsvortrags von: Herrn Waleed Sherif

Loop quantum gravity seeks a quantum description of spacetime geometry, but implementing its dynamics remains a major challenge. In the canonical formulation, physical states must satisfy quantum constraints. In the covariant formulation, transition amplitudes are assembled from local spinfoam vertex amplitudes whose evaluation is computationally demanding. In this talk, I present a research program that uses neural networks to approach both problems. For the graph-preserving canonical dynamics, I reformulate the many weak constraint equations on a fixed graph as a single ground state search problem, enabling one to find approximate physical states using variational Monte Carlo methods and neural quantum states. Focusing on a 4-dimensional model with Euclidean dynamics in the weak coupling limit, I show how, using this framework, one can find approximate solutions and probe them using geometric operators and correlation functions. In particular, I consider how ordering affects the approximate solutions found, and establish connections with known kinematical vacua.For the covariant form of the dynamics, I investigate supervised neural surrogates for the Euclidean Barrett-Crane vertex amplitude. The learning problem separates into identifying configurations with non-zero amplitudes and approximating their magnitudes. The results show that, with the network architectures used, support classification transfers beyond the training data used whereas magnitude regression reproduces the reference data but does not perform well beyond it. I conclude by discussing the scope of these results and the extensions required to study more general canonical dynamics and Lorentzian spinfoam models.

(Vortrag auf Englisch)

Dem Vortrag schließt sich eine Diskussion von 15 Minuten an. Vortrag und Diskussion sind öffentlich. Diesen Verfahrensteilen folgt ein nicht öffentliches Rigorosum von 45 Minuten.