  The turbulence in the diffuse intergalactic medium (IGM) plays an important
role in various astrophysical processes across cosmic time, but it is very
challenging to constrain its statistical properties both observationally and
numerically. Via the statistical analysis of turbulence along different
sightlines toward a population of fast radio bursts (FRBs), we demonstrate that
FRBs provide a unique tool to probe the intergalactic turbulence. We measure
the structure function (SF) of dispersion measures (DMs) of FRBs to study the
multi-scale electron density fluctuations induced by the intergalactic
turbulence. The SF has a large amplitude and a Kolmogorov power-law scaling
with angular separations, showing large and correlated DM fluctuations over a
range of length scales. Given that the DMs of FRBs are IGM dominated, our
result tentatively suggests that the intergalactic turbulence has a Kolmogorov
power spectrum and an outer scale on the order of $100$ Mpc.
