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MON: Monday Contributed Sessions

MON 23: Poster Session: Fundamental Aspects and Model Systems

MON 23.16: Poster

Montag, 8. September 2025, 18:30–20:30, ZHG Foyer 1. OG

Quenching on the circle: how compactification curbs entanglement growth in coupled rotors — •Stefan Aimet¹, Philipp Schmoll¹, Jens Eisert¹, and Spyros Sotiriadis² — ¹Freie Universität Berlin, Berlin, Germany — ²University of Crete, Heraklion, Greece

Entanglement entropy is a powerful diagnostic of non-equilibrium dynamics in quantum (many-body) systems. In Gaussian models, however, freely diffusing zero modes – such as those arising in two coupled harmonic oscillators subjected to a global quench that drives the on-site frequency to zero – lead to unbounded, logarithmic growth of entanglement entropy. To remedy this pathology, we compactify each coordinate on a circle, thereby mapping the system to two coupled quantum rotors with a discrete spectrum. Because the quench injects only a finite amount of energy, the dynamics remain confined to an effective finite-dimensional Hilbert space, thereby capping entanglement growth. We analyze the entanglement dynamics across various parameter regimes, and we confirm qualitatively similar bounding of entanglement growth in an N-site rotor chain via matrix-product-state simulations. Our results highlight the crucial role of compact topology in curbing entanglement growth during non-equilibrium dynamics and motivate further theoretical and experimental exploration of compactified quantum systems.

Keywords: quench; entanglement; compact; coupled rotor; quantum