The open lecture “SQUID metamaterials: A testbed for nonlinear dynamics” by Dr. Ioanna Chitzanidi (University of Crete, Greece) will be held in NUST MISIS on 27 of September 2019 at 14:00.

 

Abstract: The Superconducting QUantum Interference Device (SQUID) is a highly  nonlinear oscillator with rich dynamical behavior. In the present talk, the dynamical properties of the SQUID in the strongly nonlinear regime are demonstrated using a well-established model whose parameters lie in the experimentally accessible range of values. 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. This effect is manifested by a “snake-like” form of the resonance curve. In the presence of both ac and dc flux, multiple bifurcation sequences and secondary resonance branches appear at frequencies above and below the geometric resonance. In the latter case, the SQUID exhibits chaotic behavior in large regions of the parameter space. 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. Using Fourier analysis we charaterize these patterns and identify characteristic spatial and temporal periods. The obtained patterns occur near the synchronization-desynchronization transition which is related to the bifurcation scenarios of the single SQUID. The latter provides useful insight into the obtained collective states. Chimeras emerge due to the multistability near the geometric resonance, and by varying the dc component of the external force we can make them appear and reappear and, also, control their location.

 

Venue: NUST MISIS (Moscow, Leninsky prospect, 4), main building, conference-hall № Б-607 (6th floor)

 

Everyone is welcome!