Modeling of LC-shunted intrinsic Josephson junctions in high-T _c superconductors

Abstract

Resonance phenomena in a model of intrinsic Josephson junctions shunted by LC-elements (L-inductance, C-capacitance) are studied. The phase dynamics and IV-characteristics are investigated in detail when the Josephson frequency approaches the frequency of the resonance circuit. A realization of parametric resonance through the excitation of a longitudinal plasma wave, within the bias current interval corresponding to the resonance circuit branch, is demonstrated. It is found that the temporal dependence of the total voltage of the stack, and the voltage measured across the shunt capacitor, reflect the charging of superconducting layers, a phenomenon which might be useful as a means of detecting such charging experimentally. Thus, based on the voltage dynamics, a novel method for the determination of charging in the superconducting layers of coupled Josephson junctions is proposed. A demonstration and discussion of the influence of external electromagnetic radiation on the IV-characteristics and charge-time dependence is given. Over certain parameter ranges the radiation causes an interesting new type of temporal splitting in the charge-time oscillations within the superconducting layers.

Noise and disorder effects in a series of birhythmic Josephson junctions coupled to a resonator

“…First, this is a proof of principle for relatively few JJ and secondly to a specific configuration of the external load. It would be interesting to extend the investigation to other configurations [26,27], to investigate the role of the resonator and JJ parameters, and to consider many more JJs. The latter case calls for much more demanding numerical simulations, that presumably are only possible with massive parallel computations, possibly on cheap CUDA hardware [39].…”

“…For example in [23] each junction is coupled to the resonator and the junctions are coupled to each other through the capacitance. Possible coupling mechanisms are RLC circuits [24,25], or LC circuits [26], that allow the possibility of parametric resonance [27]. Thus, it has been possible to derive the properties of the synchronized and unsynchronized states, to characterize the conditions that favor synchronization, especially the coupling circuit configuration and the bias point [26,27], that are the parameters most easily tuned in experiments.…”

Stochastic first passage time accelerated with CUDA

“…Eqs. (9,10,11) constitute the physical setting in which we describe the method for accelerated computation of the FPTs.…”

“…The evolution of a JJ according to the Langevin Eqs. (9,10,11) is the basis to evaluate the exit time, that is the practically available physical quantity. Schematically, the trajectories that determine the random exit times are represented in Fig.…”

“…Kramers' rate theory [2,3]). From the experimental point of view, in Josephson Junctions (JJ) superconducting devices [4] the measurement of the threshold for the escapes is the only possibility (or the simplest way) to gain information on the internal dynamics of systems as quantum devices [5,6], threshold detectors [7][8][9] and arrays of JJ [10,11] of great interest for high frequency, up to the THz region, local oscillators [12]. The threshold for escapes is an essential physical information also in diverse systems .…”