  We present evidence of a large angle correlation between the cosmic microwave
background measured by WMAP and a catalog of photometrically detected quasars
from the SDSS. The observed cross correlation is (0.30 +- 0.14) microK at zero
lag, with a shape consistent with that expected for correlations arising from
the integrated Sachs-Wolfe effect. The photometric redshifts of the quasars are
centered at z ~ 1.5, making this the deepest survey in which such a correlation
has been observed. Assuming this correlation is due to the ISW effect, this
constitutes the earliest evidence yet for dark energy and it can be used to
constrain exotic dark energy models.
