Macroscopic quantum effects in the resistive states of Josephson coupled systems

In this report I present a theoretical study of macroscopic quantum coherent effects in the resistive (whirling) state of dc driven Josephson junction arrays. The current-voltage characteristics of such systems display resonant steps that are due to the resonant interaction between the time dependent Josephson current and the excited electromagnetic oscillations (EOs). The voltage positions of the resonances are determined by the transitions between the discrete energy levels in the spectrum of EOs. We show that in the quantum regime as the system is driven on the resonance, coherent Rabi oscillations between the quantum levels of EOs occur. At variance with the classical regime the magnitude and the width of resonances are determined by the incoherent relaxation processes or the frequency of Rabi oscillations that in turn, depends on an externally applied magnetic field and the parameters of the system.