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CPB Superconducting Qubit

This program plots several relevant values in a CPB qubit as a function of the control parameter x (the gate charge in units of electron charge). The top two sliders are used to set the Coulomb energy (capacitive) constant (Ec) and the Josephson Constant EJ. The red and blue curves represent the kinetic energies associated to the lowest energy charge states. Green and orange dashed curves represent the approximate energies one the Josephson constant is taken into account (notice the avoided crossing). The magenta curve represents half of the angle between the Bloch vector of the approximate eigenstates of the Hamiltonian and th z direction. The Vg slider just displaces the vertical Qg segment to mark a working point.