Experimental evidence of double explosive synchronization in multilayer oscillator networks.

Explosive synchronization (ES) is characterized by irreversible transitions to collective coherence in coupled oscillator networks. A recent study [Phys. Rev. Res. 4, 033009 (2022)2643-156410.1103/PhysRevResearch.4.033009] has predicted a richer phenomenon, double explosive synchronization (DES), in which a multilayer system exhibits two consecutive discontinuous transitions. Experimental evidence of DES, however, has remained lacking. Here we report the experimental observation of DES using multilayer networks of Wien-bridge oscillators. By coupling a strongly synchronized low-frequency driving layer to a weakly synchronized high-frequency controlled layer and gradually varying the interlayer coupling, we observe two distinct hysteretic transitions accompanied by bistability. Complementary LTspice circuit simulations reproduce the experimental behavior. These results establish DES as a robust and physically realizable phenomenon in multilayer oscillator networks.