报告题目：The Nature of Abrupt Transitions in Interdependent Superconducting Networks

报 告 人: Aviad Frydman，Department of Physics, Bar Ilan University

报告时间：2025年5月12日14:00

报告地点：物理楼W361

内容摘要：Phase transitions are central to statistical physics. While continuous transitions are well understood, the mechanisms behind abrupt transitions remain elusive. In my talk I will present experimental results showing that abrupt phase transitions can arise from internal random cascading processes triggered by dependency interactions, where a local event induces a global phase shift.The basis for this understanding stems from “Interdependent Network theory” [1] that asserts that the existence of two distinct types of interactions, connectivity within each network and dependency between networks, produce cascading failures and discontinuous transitions, with broad applications in complex infrastructures. Our group was the first to experimentally realize this theory in a physical system, interdependent superconducting networks [2], where two superconducting networks interact with two types of interactions, current flow within each network, and Joule heat dissipation between the networks.  Our experiments reveal that the abrupt transitions in these systems stem from a unique metastable state, characterized by a long-lived “resistance plateau.” During this plateau, random cascading events spontaneously occur across the system, lasting thousands of seconds, before the system abruptly transitions to a new global state. The duration of this plateau scales with both the size of the system and its distance from the critical point, obeying predicted critical exponents. Furthermore, like epidemic spreading, these changes are characterized by a branching factor, a measure of how perturbations spread, which equals exactly one at the critical point and deviates from one off criticality.I will also discuss how limiting range dependency interactions can localize disruptions yet still induce global transitions, and show that similar phenomena arise even in single networks with two distinct interactions, thus broadening the applicability of this framework to a wide range of physical systems.

[1] S. V. Buldyrev, R. Parshani, G. Paul, H. E. Stanley, and S. Havlin. “Catastrophic cascade of failures in interdependent networks”. Nature 464.7291 (2010).

[2] I. Bonamassa, B. Gross, M. Laav, I. Volotsenko, A. Frydman and S. Havlin. “Interdependent superconducting networks”. Nature Physics 19 (2023).