  Quantum information processors greatly benefit from high clock frequency to
fully harnessing the quantum advantages before they get washed out by the
decoherence. In this pursuit, all-optical systems offer unique advantages due
to their inherent 100 THz carrier frequency, permitting one to develop THz
clock frequency processors. In practice, the bandwidth of the quantum light
sources and the measurement devices has been limited to the MHz range and the
generation rate of nonclassical states to kHz order -- a tiny fraction of what
can be achieved. In this work, we go beyond this limitation by utilizing
optical parametric amplifier (OPA) as a squeezed-light source and optical
phase-sensitive amplifiers (PSA) to realize high-rate generation of broadband
non-Gaussian states and their quantum tomography. Our state generation and
measurement system consists of a 6-THz squeezed-light source, a 6-THz PSA, and
a 66-GHz homodyne detector. With this system, we have successfully demonstrated
non-Gaussian state generation at a 0.9 MHz rate -- almost three orders of
magnitude higher than the current state-of-the-art experiments -- with a
sub-nanosecond wave packet using continuous-wave laser. The performance is
constrained only by the superconducting detector's jitter which currently
limits the usable bandwidth of the squeezed light to 1 GHz, rather than the
optical and electronic systems. Therefore, if we can overcome the limitation of
the timing jitter of superconducting detector, non-Gaussian state generation
and detection at GHz rate, or even THz rate, for optical quantum processors
might be possible with OPAs.
