1. A logic device using quantum polarization states of single photons, comprising: a first polarizing beam splitter having a first plurality of input spatial modes and a first plurality of output spatial modes for a first set of orthogonal polarizations; a second polarizing beam splitter having a second input spatial mode and a second plurality of output spatial modes for a second set of orthogonal polarizations different from the first set, the second input spatial mode aligned with a first detected output spatial mode of the first plurality of output spatial modes; a first plurality of single photon detectors, each single photon detector disposed along a different one of the second plurality of output spatial modes; and a first device output that carries an output photon based in part on a number of photons detected by the first plurality of single photon detectors, wherein a polarizing beam splitter for a particular set of orthogonal polarizations transmits a photon that arrives on a particular input spatial mode with one polarization of the particular set onto one output spatial mode, and transmits a photon that arrives on the particular input spatial mode with a different polarization of the particular set onto a different output spatial mode.