Inhomogeneous reionization and the polarization of the cosmic microwave background

In a universe with inhomogeneous reionization, the ionized patches create a second-order signal in the cosmic microwave background polarization anisot ropy. This signal originates in the coupling of the free-electron fluctuati on to the quadruple moment of the temperature anisotropy. We examine the co ntribution from a simple inhomogeneous reionization model and find that the signal from such a process is below the detectable limits of the Planck Su rveyor mission. However, the signal is above the fundamental uncertainty li mit from cosmic variance, so that a future detection with a high-accuracy e xperiment on subarcminute scales is possible.