New Perspectives in Quantum Field Theory: From Quantum to Classical Simulation

by Prof. Spyros Sotiriadis (University of Crete (GR))

Wednesday 26 Nov 2025, 17:00 → 18:00 Asia/Nicosia

B228 (ΘΕΕ02)

Abstract: Quantum field theory (QFT) provides the framework for describing a vast range of physical phenomena in particle physics, cosmology, and black-hole physics. However, understanding entanglement—both in equilibrium and during real-time dynamics—remains a major challenge. In this talk, I will present two complementary approaches to this problem, combining quantum and classical simulations. On the experimental side, ultracold atom platforms implementing one-dimensional tunnel-coupled Bose gases act as analog quantum simulators of interacting QFTs. Using a tomography protocol tailored to continuous fields, we reconstruct the system’s quantum state and directly measure von Neumann entropies and mutual information, revealing the scaling of entanglement in thermal and out-of-equilibrium states. On the theoretical side, I will introduce a new numerical method for simulating 1+1D QFTs that merges Hamiltonian Truncation with Tensor Network techniques. This approach enables the study of low-energy spectra and real-time quench dynamics in models such as sine-Gordon and massive Schwinger, providing a classical counterpart to quantum simulation experiments and offering new perspectives on entanglement and thermalisation in QFT.

Speaker: Spyros Sotiriadis received a B.Sc. in Physics from the National and Kapodistrian University of Athens in 2005, an M.Sc. in Mathematics and Theoretical Physics from Cambridge University in 2006 and a Ph.D. in Theoretical Physics from Oxford University in 2010. In his PhD thesis he studied the out-of-equilibrium dynamics of quantum field theory models after abrupt parameter changes ("Quantum Quenches in Extended Systems"). From 2009 to 2022 he worked as a researcher at universities or research institutions in Italy (SISSA, Pisa University, University Roma III), Slovenia (University of Ljubljana) and Germany (Freie Universität Berlin). He has been the Principal Investigator of three research grants, including the Marie Skłodowska-Curie Action "TNTCSA" (Grant agreement ID: 101030988) funded by the European Commission. He was elected Assistant Professor at the Department of Physics of the University of Crete in 2021. Prof. Sotiriadis' research interests span a wide range, such as out-of-equilibrium dynamics of many-body quantum systems, entanglement, quantum transport, quantum chaos, analytical and numerical methods based on quantum field theory, conformal field theory, integrability, and applications to condensed matter and atomic physics.