$\epsilon = I _{p,A}\Phi _{0}/k _{B}T \approx 1000$.

![\[fig:epsart\] Current-voltage characteristics of the DDCI structures with square side of the loops $a \approx  4 \ \mu m$ measured at the temperature $T \approx 0.44 \ K $ and different magnetic field $B \approx 9.2 \ Oe$ and $B \approx 10.2 \ Oe$. Two extra steps correspond to the two additional Josephson junctions of the real DDCI at $ l _{u}$ and $r _{d}$.](Fig4)

The experimental corroboration of the voltage jumps, Fig.3, is the central objective of our measurements of the real double contour interferometer shown on Fig.2. Other peculiarities observed at these measurements are considered partly in the Supporting Information. Here we say only about the periodical modulation of the jump amplitude, Fig.3, and some peculiarities of the current-voltage characteristics of the real structures. We assume that the modulation of the jump $V _{max} - V _{min}$ with the period of $B _{m} \approx 0.8 \ Oe $ may be connected with the shift $\approx 0.5 \ \mu m $ of the loops relative to one another in the measured structure, Fig.2, see the Supporting Information. Three steps at the current-voltage characteristics shown in Fig. 4 are observed because of 