Istituto dei sistemi complessi (ISC)



SPIKY (Kreuz et al., 2015) is a graphical user interface written in Matlab which facilitates the analysis of electrophysiological data such as the EEG and neuronal spike trains (sequences of electrical action potentials emitted by neurons). In addition to the standard Peri-Stimulus Time Histogram (PSTH) it contains several time-resolved measures of spike train synchrony which were all developed in our lab: ISI-distance, SPIKE-distance, and SPIKE synchronization. For a given data set SPIKY ...

Diffusion, what else?

Diffusion essentially refers to a motion which leads to the spreading of some quantity: density of particles, energy, and so on. It owes its universality to the central limit theorem, according to which che combination of independent, random events has general features not related to the details of the single events. For example, in a standard, diffusive motion the spreading quantity does not vary proportionally to the time, but its variation may double only if time quadruples! If however the ...

Physical realization of the Glauber quantum oscillator

More than 30 years ago, Glauber theorized the existence of quantum systems to explain the link between the reversible microscopic and irreversible macroscopic scale. The formulation of such model is based on the so-called "rigged Hilbert space" and include irreversibility as a fundamental principle through the introduction of an inverted harmonic oscillator describing quantum amplifier. The standard quantum mechanics does not forbid time-travel. However, according to the Glauber theory a quantum ...

Silent Flocks

A paper on the collective behaviour of bird flocks, in which a spin wave model is brought to the continuous limit as in fluid elements of a large hydrodynamic system, has been published in Physical Review Letters and it has been the subject of a synopsis in the APS magazine Physics. Both spin and density waves can propagate throughout flocks, but in some cases their contributions are quickly damped. Andrea Cavagna's group at ISC has shown that only spin waves propagate in medium-to-small ...

The classical and quantum dynamics of molecular spins grafted on graphene

The effect of graphene phonons and electrons on the spin dynamics of molecules grafted on graphene was investigated in a paper published in Nature Materials (C.Cervetti, A.Rettori, M.G.Pini, A.Cornia, A.Repollés, F.Luis, M.Dressel, S.Rauschenbach, M.Burghard, and L.Bogani). Dirac electrons introduce dominant quantum-relaxation channels and allow reaching a quantum tunneling regime, that was predicted 20 years ago by the French physicist Jacques Villain. A novel theoretical background is ...