Dresden 2026 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
TT: Fachverband Tiefe Temperaturen
TT 19: Focus Session: New Routes to Localization and Quantum Non-Ergodicity II (joint session TT/DY)
TT 19.8: Talk
Monday, March 9, 2026, 17:00–17:15, CHE/0091
Dynamics in the presence of local symmetry-breaking impurities — •Yahui Li1,2, Pablo Sala3,4, Frank Pollmann1,2, Sanjay Moudgalya1,2, and Olexei Motrunich3,4 — 1Technical University of Munich, Germany — 2Munich Center for Quantum Science and Technology, Germany — 3California Institute of Technology, USA — 4Walter Burke Institute for Theoretical Physics, USA
Continuous symmetries lead to universal slow relaxation of correlation functions in quantum many-body systems. In this talk, I will show how local symmetry-breaking impurities affect the dynamics of these correlation functions using Brownian quantum circuits. While explicitly breaking the symmetry is generally expected to lead to eventual restoration of full ergodicity, we find that approximately conserved quantities that survive under such circumstances can still induce slow relaxation. This can be understood using a super-Hamiltonian formulation, where low-lying excitations determine the late-time dynamics. We show that in one dimension, symmetry-breaking impurities modify diffusive and subdiffusive behaviors associated with U(1) and dipole conservation at late times, e.g., by increasing power-law decay exponents of the decay of autocorrelation functions. On the other hand, for an impurity that disrupts strong Hilbert space fragmentation, it leads to prethermal plateaus in autocorrelation functions. Overall, our approach systematically characterizes how symmetry-breaking impurities affect relaxation dynamics in symmetric systems.
Keywords: Quantum circuits; Quantum many-body systems; Hydrodynamics; Symmetries in condensed matter