  We investigate the confinement-deconfinement phase transition at finite
temperature of the SU(3) Yang-Mills(YM) theory on the lattice from a viewpoint
of the dual superconductor picture based on the novel reformulation of the YM
theory. In particular, we compare the conventional Abelian dual superconductor
picture with the non-Abelian dual superconductor picture proposed in our
previous works as the mechanism of quark confinement in the SU(3) YM theory.
For the SU(3) YM theory, the reformulation allows two possible options called
maximal and minimal. The maximal option corresponds to the manifestly
gauge-invariant extension of the Abelian projection scheme, while the minimal
option is really new to give the non-Abelian dual superconductor picture.
Keeping these differences in mind, we present the numerical evidences that the
confinement/deconfinement phase transition is caused by
appearance/disappearance of the dual Meissner effects. First, we measure the
Polyakov loop average at various temperatures to determine the critical
temperature separating the low-temperature confined phase and the
high-temperature deconfined phase. Second, we measure the static
quark-antiquark potential. Third, we measure the chromoelectric and
chromomagnetic flux created by a pair of quark and antiquark at temperatures
below and above the critical temperature. We observe no more squeezing of the
chromoelectric flux tube above the critical temperature. Finally, we measure
the associated magnetic--monopole current induced around the chromo-flux tube
and observe that the confinement/deconfinement phase transition is associated
with the appearance/disappearance of the induced magnetic--monopole current,
respectively. We confirm that these results are also obtained by the restricted
field alone in both options, indicating the restricted field dominance in quark
confinement at finite temperature.
