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SYNP: Symposium New Trends in Nonequilibrium Physics: Conservation Laws and Nonreciprocal Interactions

SYNP 1: New Trends in Nonequilibrium Physics: Conservation Laws and Nonreciprocal Interactions

SYNP 1.4: Invited Talk

Thursday, March 21, 2024, 16:45–17:15, H 0105

Phase transitions and fluctuations of nonreciprocal systems — •Sarah A.M. Loos — DAMTP, University of Cambridge, Cambridge, UK

Reciprocity is a hallmark of thermal equilibrium, but ubiquitously broken in far-from-equilibrium systems. I will give some insights into how nonreciprocal interactions can fundamentally affect the phases and fluctuations of many-body systems. Using a two-dimensional XY model, where spins interact only with neighbours within their ‘vision cones’, we show how nonreciprocity can lead to true long-range order and directional propagation of defects [1]. In binary fluids, nonreciprocal coupling between fluid components can cause the emergence of travelling waves through PT symmetry-breaking phase transitions. Using a nonreciprocal field theory, we show that fluctuations not only inflate, as in equilibrium criticality, but also develop an asymptotically increasing time-reversal asymmetry [2-4]. The formation of dissipative patterns and the emergence of irreversible fluctuations can both be attributed to a mechanism of mode coupling in the vicinity of critical exception points, which manifests itself in actively propelled interface dynamics [4].

[1] SL, Klapp & Martynec, Phys. Rev. Lett. 130, 198301 (2023)

[2] Suchanek, Kroy & SL, Phys. Rev. Lett. 131, 258302 (2023)

[3] Suchanek, Kroy & SL, Phys. Rev. E 108, 064123 (2023)

[4] Suchanek, Kroy & SL, Phys. Rev. E 108, 064610 (2023)

Keywords: Nonreciprocal interactions; Irreversibility; Dissipative pattern formation; Critical exceptional points; Nonequilibrium phase transitions