Figure 1

(Color online) Schematic diagram of a hybrid quantum circuit with the charge (left-hand side) and flux (right-hand side) qubits connected to a large (middle) Josephson junction (JJ). In the charge qubit, the two JJs have the same Josephson coupling energy $E_{J1}$ and capacitance $C_J$. In the flux qubits, two JJs have the same Josephson coupling energy $E_{J2}$ and capacitance $C_f$; the third JJ has a smaller Josephson coupling energy $\alpha E_{J2}$ and capacitance $\alpha C_f$, where $0.5<\alpha <1$. The large JJ in the middle has the Josephson coupling energy $E_{J0}$ and capacitance $C_0$. For the ideal hybrid circuit, $E_{J0}⪢E_{J2}⪢E_{J1}$. Here the arrow near each JJ denotes the chosen direction for the positive phase drop across the corresponding junction.Reuse & Permissions