Rotating unstable Langevin-type dynamics: linear and nonlinear mean passage time distributions

Detection of weak signals through nonlinear relaxation times for a Brownian particle in an electromagnetic field

The detection of weak signals through nonlinear relaxation times for a Brownian particle in an electromagnetic field is studied in the dynamical relaxation of the unstable state, characterized by a two-dimensional bistable potential. The detection process depends on a dimensionless quantity referred to as the receiver output, calculated as a function of the nonlinear relaxation time and being a characteristic time scale of our system. The latter characterizes the complete dynamical relaxation of the Brownian particle as it relaxes from the initial unstable state of the bistable potential to its corresponding steady state. The one-dimensional problem is also studied to complement the description.

Detection of weak and large electric fields through the transient dynamics of a Brownian particle in an electromagnetic field

In this work we present a mechanism to detect the presence of an external electric field of either weak or large amplitude by means of the decay process from an unstable state, described by a bistable potential, of an electrically charged Brownian particle embedded in a uniform electromagnetic field. Since the detection process takes place around the initial unstable state of the bistable potential, our theoretical description is given in the linear approximation of the aforementioned potential. The decay process is characterized through the statistics of the passage time distribution calculated by means of two theoretical approaches relying on the overdamped Langevin equation: one is the quasideterministic approach valid for large times and used for the detection of weak signals, whereas the other one is the rotational approach, valid for intermediate times and adequate for the detection of large electric-field amplitudes.

Non-Markovian rotating unstable processes driven by Gaussian colored noise

In this paper the statistical properties of the mean passage time distribution are used to characterize the decay process of non-Markovian rotating unstable processes driven by Gaussian colored noise and subjected to the influence of a constant external force. The time characterization will be linear and studied in two limiting cases: large and intermediate times. General systems of two variables are studied. In both schemes we show that, for small correlation time of the noise, the non-Markovian effects are taken into account by an effective noise intensity. To compare qualitatively the non-Markovian time scale with respect to the Markovian case, we apply those results to determine the detection bandwidth of a large external signal in a laser system.