Quantum Analog of Bifurcation and Switching Effects in a Nonlinear Josephson Oscillator.

We theoretically study a nonlinear Josephson oscillator (Josephson junction) in the effective potential, which form is a result of a driving current. We first consider the phase dynamics in the classical regime and then explore the problem in the quantum regime by solving the energy eigenvalue problem. Here we are going to pay special attention to the study of the effects of switching between the states of a nonlinear oscillator separated by a separatrix. For this purpose, we consider controlling the oscillator with a "two-color" current. In the classical view, the first high-frequency current component brings the oscillator to the bifurcation point. A second modulated high-frequency component produces a programmed system switching. A similar scenario is considered in the quantum regime. [ABSTRACT FROM AUTHOR]