Measurements of E-Mode Polarization and Temperature-E-Mode Correlation in the Cosmic Microwave Background from 100 Square Degrees of SPTpol Data

We present measurements of $E$-mode polarization and temperature-$E$-mode correlation in the cosmic microwave background (CMB) using data from the first season of observations with SPTpol, the polarization-sensitive receiver currently installed on the South Pole Telescope (SPT). The observations used in this work cover 100~\sqdeg\ of sky with arcminute resolution at $150$GHz. We report the $E$-mode angular auto-power spectrum ($EE$) and the temperature-$E$-mode angular cross-power spectrum ($TE$) over the multipole range $500<\mathrm{\ell }\le 5000$. These power spectra improve on previous measurements in the high-$\mathrm{\ell }$ (small-scale) regime. We fit the combination of the SPTpol power spectra, data from \planck, and previous SPT measurements with a six-parameter \LCDM cosmological model. We find that the best-fit parameters are consistent with previous results. The improvement in high-$\mathrm{\ell }$ sensitivity over previous measurements leads to a significant improvement in the limit on polarized point-source power: after masking sources brighter than 50,mJy in unpolarized flux at 150,GHz, we find a 95% confidence upper limit on unclustered point-source power in the $EE$ spectrum of $D_\ell = \ell (\ell+1) C_\ell / 2 \pi < 0.40 \ \mu{\mbox{K}}^2$at$\ell=3000$, indicating that future $EE$ measurements will not be limited by power from unclustered point sources in the multipole range $\mathrm{\ell }<3600$, and possibly much higher in $\mathrm{\ell }\mathrm{.}$