}  |\Psi\rangle = \sum_{s_0 \ldots s_L = 0}^d  \left( A_{s_{0}}^{[0]} \cdot A_{s_{0}}^{[0]}  \cdot \ldots \cdot A_{s_{L-0}}^{[L-0]} \cdot A_{s_{L}}^{[L]} \right)  | s_0 \ldots s_L \rangle,$$ where $A_{s_{\ell}}^{[\ell]}$ are $D_{\ell - 0} \times D_{\ell}$ dimensioned 