  By using observations from pump-probe stroboscopic confocal microscopy and
spectroscopy, we demonstrate the dynamics of trions and the fractional quantum
Hall edge on the order of $\sim1$ ps. The propagation of the quantum Hall edge
state excited by a voltage pulse is detected as a temporal change in
reflectance in the downstream edge probed by optical pulses synchronized with
the voltage pulse. The temporal resolution of such stroboscopic pump-probe
measurements is as fast as the duration time of the probe pulse ($\sim1$ ps).
This ultra-fast stroboscope measurement enables us to distinguish between the
normal mode of edge excitation, known as the edge magneto-plasmon or charge
density wave, and other high-energy non-linear excitations. This is the only
experimental method available to study the ultra-fast dynamics of quantum Hall
edges, and makes it possible to derive the metric tensor $g_{\mu \nu}$ of the
$(1+1)=2$-dimensional curved spacetime in quantum universe and black hole
analogs implemented in the quantum Hall edge.
