Fig. 2: Feedback driven RCSJ regimes.
a The minimum and maximum values of x2 (proportional to the junction voltage) as a function of the reduced bias current ib = Ib/Ic. We identify three different regimes, shadowed with orange, blue, and purple backgrounds. b-d Evolution of the current [\(i=\sin ({x}_{1})\)] and the voltage (x2) through the junction at different times. The color in each panel represents schematically the regime, following the color of the dots in (a). In (b) the junction quickly reaches a stable state with a time-independent finite current and zero voltage (stable regime). In (c) the junction leaves the zero voltage state and oscillates between a zero and a finite voltage state (bistable regime). Oscillations are spontaneous, i.e. without the action of an external AC drive. In (d) both the current and the voltage oscillate at frequency \(\frac{2\pi }{{\tau }_{{{\rm{J}}}}}\) (periodic regime), but the current averages to zero while the voltage averages to a finite value. e x2 vs time (blue line) together with the feedback term multiplied by 2β (black line), see Eq. (1). Parameters in these simulations are T = 0 K, β = 2, τD = 105 and Δτ = 6 ⋅ 103 (both τD and Δτ in units of τJ).
