  Photo-excitation is a very powerful way to instantaneously drive a material
into a novel quantum state without any fabrication, and variable ultrafast
techniques have been developed to observe how electron-, lattice-, and
spin-degrees of freedom change. One of the most spectacular phenomena is
photo-induced superconductivity, and it has been suggested in cuprates that the
transition temperature Tc can be enhanced from original Tc with significant
lattice modulations. Here we show another photo-induced high-Tc superconducting
state in the iron-based superconductor FeSe with semi-metallic hole and
electron bands. The transient electronic state in the entire Brillouin zone is
directly observed by the time- and angle-resolved photoemission spectroscopy
using extreme ultraviolet pulses obtained from high harmonic generation. Our
results of dynamical behaviors on timescales from 50 fs to 800 ps consistently
support the favorable superconducting state after photo-excitation well above
Tc. This finding demonstrates that multiband iron-based superconductors emerge
as an alternative candidate for photo-induced superconductors.
