Noise-induced nucleation in a bistable tunnel diode circuit

We report the measurement of first-passage time distributions associated with electrical current switching in a bistable tunnel diode circuit driven by a noise generator with adjustable noise intensity $D$. In such a system, it is particularly interesting to study the behavior of the mean switching time $\tau $ near the boundary of the bistable regime where the metastable state approaches and collides with a saddle point in the underlying noise-free dynamical system. In the tunnel diode circuit and for sufficiently large noise intensity, we find a \textit{linear} scaling relationship $\ln \tau \propto \left| {V-V_{th} } \right|/D$ valid over several decades of time, where $V$ denotes the applied voltage and $V_{th}$ denotes the value corresponding to the end of the bistable regime. At smaller noise intensities, we typically find that the mean switching time versus $V-V_{th}$ possesses multiple scaling regimes. These experimental results are interpreted in light of theoretical work that shows how lateral charge transport dynamics can strongly affect the noise-induced nucleation events that lead to current switching [1]. [1] O. A. Tretiakov and K. A. Matveev, Phys. Rev. B \textbf{71}, 165326 (2005).