Evidence for Gravitational Lensing of the Cosmic Microwave Background
  Polarization from Cross-correlation with the Cosmic Infrared Background
  We reconstruct the gravitational lensing convergence signal from Cosmic
Microwave Background (CMB) polarization data taken by the POLARBEAR experiment
and cross-correlate it with Cosmic Infrared Background (CIB) maps from the
Herschel satellite. From the cross-spectra, we obtain evidence for
gravitational lensing of the CMB polarization at a statistical significance of
4.0$\sigma$ and evidence for the presence of a lensing $B$-mode signal at a
significance of 2.3$\sigma$. We demonstrate that our results are not biased by
instrumental and astrophysical systematic errors by performing null-tests,
checks with simulated and real data, and analytical calculations. This
measurement of polarization lensing, made via the robust cross-correlation
channel, not only reinforces POLARBEAR auto-correlation measurements, but also
represents one of the early steps towards establishing CMB polarization lensing
as a powerful new probe of cosmology and astrophysics.
