  Secondary anisotropies of the cosmic microwave background (CMB) can be
detected by using the cross-correlation between the large-scale structure (LSS)
and the CMB temperature fluctuations. In such studies, chance correlations of
primordial CMB fluctuations with the LSS are the main source of uncertainty. We
present a method for reducing this noise by exploiting information contained in
the polarisation of CMB photons. The method is described in general terms and
then applied to our recently proposed optimal method for measuring the
integrated Sachs-Wolfe (ISW) effect. We obtain an expected signal-to-noise
ratio of up to 8.5. This corresponds to an enhancement of the signal-to-noise
by 23 per cent as compared to the standard method for ISW detection, and by 16
per cent w.r.t. our recently proposed method, both for the best-case scenario
of having perfect (noiseless) CMB and LSS data.
