  The reconstruction method was proposed more than a decade ago to boost the
signal of baryonic acoustic oscillations measured in galaxy redshift surveys,
which is one of key probes for dark energy. After moving the observed
overdensities in galaxy surveys back to their initial position, the
reconstructed density field is closer to a linear Gaussian field, with
higher-order information moved back into the power spectrum. We find that by
jointly analysing power spectra measured from the pre- and post-reconstructed
galaxy samples, higher-order information beyond the $2$-point power spectrum
can be efficiently extracted, which generally yields an information gain upon
the analysis using the pre- or post-reconstructed galaxy sample alone. This
opens a window to easily use higher-order information when constraining
cosmological models.
