Signatures of Dissipation Driven Quantum Phase Transition in Rabi Model.

By using the worldline Monte Carlo technique, matrix product state, and a variational approach à la Feynman, we investigate the equilibrium properties and relaxation features of the dissipative quantum Rabi model, where a two level system is coupled to a linear harmonic oscillator embedded in a viscous fluid. We show that, in the Ohmic regime, a Beretzinski-Kosterlitz-Thouless quantum phase transition occurs by varying the coupling strength between the two level system and the oscillator. This is a nonperturbative result, occurring even for extremely low dissipation magnitude. By using state-of-the-art theoretical methods, we unveil the features of the relaxation towards the thermodynamic equilibrium, pointing out the signatures of quantum phase transition both in the time and frequency domains. We prove that, for low and moderate values of the dissipation, the quantum phase transition occurs in the deep strong coupling regime. We propose to realize this model by coupling a flux qubit and a damped LC oscillator.

Multi-year self potential time series analysis in a seismic area of Southern apennines

We believe that this study has a strong role when we approach the problem of the seismic prediction. In fact, only an advanced statistical analysis of the temporal dynamics of the series can give useful information on the physical law needed to describe the phenomenological aspects of electrotelluric precursors. This approach, combined with a large network to measure the space and time patterns of telluric currents, would bring toward an estimate of the efficiency of geoelectric precursors.(AU)