  An all-optical atomic Controlled-NOT (CNOT)/polarization gate operation is
demonstrated with low light intensities in a room-temperature atomic medium.
Using a Polarization-Selective-Kerr-Phase-Shift (PSKPS) technique, a $\pi$
phase shift is written to only one of the two circularly-polarized components
of a linearly-polarized input signal field by a weak phase-control field with
"magic" detuning. At the exit of the medium, the signal field maintains its
original strength but acquires a 90$^{\rm o}$ linear polarization rotation,
demonstrating the first fast, high-fidelity CNOT/polarization gate operation in
a room-temperature atomic medium. This development opens the realm of
possibilities for potential future extremely low light level telecommunication
and information processing systems.
