Josephson Junction — Phase Qubit

RCSJ model: phase dynamics, IV characteristics & chaos
Bias I/I_c 0.90
Damping β 0.50
AC drive A 0.00
AC freq ω 0.80
V = —
State: —
The RCSJ (Resistively-Capacitively Shunted Junction) model: (ℏ/2e)C φ̈ + (ℏ/2eR)φ̇ + Icsin(φ) = I + A cos(ωt). For I < Ic the phase is locked (supercurrent). Above Ic the junction switches to the voltage state. With AC driving, Shapiro steps appear at V = nℏω/2e and chaos emerges near the hysteretic boundary.