Two schemes of multiparty quantum direct secret sharing via a six-particle GHZ state*
Xin-Wei Zha,Ruo-Xu Jiang,Min-Rui Wang
Figure 2. The flow chart of scheme 2 includes the distribution of particles sequences and corresponding unitary operations ${U}_{{}_{2}}$, ${U}_{{}_{4}}$, ${U}_{{}_{6}}$.