Tunneling out of metastable vacuum in a system consisting of two capacitively coupled phase qubits

Using a powerful combination of Coleman’s instanton technique and the method of Banks and Bender, the exponential factor for the zero temperature rate of tunneling out of metastable vacuum in a system of two identical capacitively coupled phase qubits is calculated in closed form to a second order in an asymmetry parameter for a special case of intermediate coupling $C=C_J∕2$.

Figure 1

Circuit diagram for a system consisting of two capacitively coupled CBJJs.

Figure 2

Inverted potential $U_E$ with $\eta =0$.

Figure 3

Inverted potential $U_E$ with $\eta =0.3$.

Figure 4

Contour diagram of $U_E$ with $\eta =0$.

Figure 5

Contour diagram of $U_E$ with $\eta =0.3$.