of the quantum number of one of its contours from $n$ to $n+1$ predicted in [@NANO2010]. The superconducting current between points $l _{u}$ and $r _{d}$ of DDCI, Fig.1, equals the sum $$I _{s} = I _{a}\sin  \varphi _{a} + I _{b}\sin  \varphi _{b} \eqno{(4)}$$ of the currents $I _{a}\sin  \varphi _{a}$ and $I _{b}\sin  \varphi _{b}$ through the Josephson junctions $J _{a}$ and $J _{b}$. Here $I _{a}$ and $I _{b}$ are the critical currents of the Josephson junctions; $\varphi _{a}$ and $\varphi _{b}$ are the phase differences between the up $a _{u}$, $b _{u}$ and down $a _{d}$, $b _{d}$ boundaries of the Josephson junctions. The relation $$\oint_{l}dl \bigtriangledown \varphi = 2\pi n \eqno{(5)}$$ must be valid for the both contours $l _{u} - a _{u}- r_{u} - b_{u}- l _{u}$ and $l _{d} - a _{d}- r_{d} - b_{d}- l _{d}$ due to the requirement that the complex wave function must be single-valued in any point of the circumference $l $ of each contour $\Psi = |\Psi |e^{i\varphi } =  |\Psi |e^{i(\varphi + n2\pi )}$. The relation (5) should be valid also for the contours $l _{u} - a _{u} - a _{d} - r_{d} - b_{d}- 