Quantum tunneling cyclic loop in high temperature superconductor probably is the microscopic origin of high temperature superconductivity

4-particle (electrons or electrons with hole) or higher order quantum tunne ling cyclic loops (QTCLs) in real space may play a key role in high Tc supe rconductivity. Because of the existence of mixed valences on the CuO2 plane , the electron/holes in high Tc superconductor are weekly localized and str ongly correlated thus able to form QTCL. The QTCLs have k=0 in the center o f the mass frame, and a non-zero angular momentum. Each QTCL has total spin S=0. Each QTCL can contain 2 or more Cooper pairs in real space. As a resu lt of the strong correlation between those tunneling loops, high Tc superco nductivity will occur if the connectivity of tunneling loops is large enoug h to form an infinite cluster, under these conditions: T<Tc and H<Hc. This high Tc superconducting transition is strong angular momentum related, is a special kind of percolation transition which is consistent with the experi mental results of uniaxial stress experiments and of thermal expansion meas urements. This model is consistent with the fact that the coherence length of high temperature superconductor is in the order of 5-20 angstroms. QTCL model is consistent with gauge invariance and the observation of doped carb on 60 superconductors and superfluid He-3.