From 15:00
Superconducting Metamaterials Laboratory / Nadezhda Sannikova, tel: +7 (495) 638 46 46, cell phone: +7 (929) 566 77 60
The seminar "PATTERN FORMATION AND CHIMERAS IN SQUID METAMATERIALS" by Dr. J. Hizanidis will take place in MISIS on June, 11 at 15:00.
Speaker
Dr. J. Hizanidis, Department of Physics, University of Crete, Heraklion, GR 71003, GREECE
Abstract
The radio frequency (rf) Superconducting QUantum Interference Device (SQUID) is a highly nonlinear oscillator exhibiting rich dynamical behavior [1,2]. When driven by a time-periodic (ac) flux either with or without a constant (dc) bias, the SQUID exhibits extreme multistability at frequencies around the (geometric) resonance which is manifested by a ``snake-like'' form of the resonance curve [3]. Repeating motifs of SQUIDs form metamaterials, i. e. artificially structured media of weakly coupled discrete elements that exhibit extraordinary properties e. g. negative diamagnetic permeability. We report on the emergent collective dynamics of two-dimensional lattices of coupled SQUID oscillators, which involves a rich menagerie of spatio-temporal pattern formation and chimera states [4,5]. Both types of dynamics emerge near the synchronization-desynchronization transition occurring in the driving frequency-dc bias parameter space. A continuation analysis reveals that the lines of this transition coincide with bifurcations of the single SQUID. The latter provides useful insight into the observed collective dynamics: chimeras emerge due to the snake-like form of the resonance curve, while patterns occur at lower driving frequencies, where the single SQUID is chaotic.
References:
[1] S. M. Anlage: The physics and applications of superconducting metamaterials, J. Opt. 13, 024001 (2011).
[2] N. Lazarides and G. P. Tsironis: Superconducting metamaterials. Phys. Rep. 752, 1-67 (2018).
[3] J. Hizanidis, N. Lazarides, and G. P. Tsironis, Flux bias-controlled chaos and extreme multistability in SQUID oscillators, Chaos 28 (6), 063117 (2018).
[4] M. J. Pannagio and D. Abrams, Chimera states: Coexistence of coherence and incoherence in networks of coupled oscillators, Nonlinearity 28, R67 (2015).
[5] J. Hizanidis, N. Lazarides, and G. P. Tsironis, Robust chimera states in SQUID metamaterials with local interactions, Phys. Rev. E 94, 032219 (2016).