Dresden 2026 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 34: Focus Session: Fluids with Broken Time-Reversal Symmetry – Odd/Hall Viscosity Between Active Matter and Electron Flows
DY 34.7: Talk
Wednesday, March 11, 2026, 11:30–11:45, ZEU/0160
Edge currents shape condensates in chiral active matter — •Boyi Wang1,2, Patrick Pietzonka4, and Frank Jülicher1,2,3 — 1Max Planck Institute for the Physics of Complex Systems, Dresden, Germany — 2Center for Systems Biology Dresden, Dresden, Germany — 3Cluster of Excellence Physics of Life, TU Dresden, Germany — 4SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
Chiral active matter, which breaks both parity symmetry and detailed balance, is widespread in living systems. Here, we introduce a minimal two-dimensional chiral active Ising model by incorporating stochastic, biased local rotations. At low temperatures, the system coarsens into condensates with chiral orientations and faceted, crystal-like shapes rather than circular ones observed under Kawasaki dynamics. The interfaces align at characteristic angles to the lattice axes and support persistent, unidirectional, angle-dependent edge currents.
To generalise these results, we develop a continuum theory by adding an active edge-current term to Model B. An edge current with n-fold symmetry produces condensates with corresponding n-fold polygonal shapes. In the sharp-interface limit, we construct an effective active surface potential that predicts the steady-state condensate geometry, consistent across both the lattice model and the continuum description.
Our results reveal how local chiral activity generates global edge currents and demonstrate their fundamental role in governing phase separation and interfacial dynamics in chiral active systems.
Keywords: chiral; edge current; phase separation; ising model; model B