Dipole blockade through Rydberg Forster resonance energy transfer

High resolution laser excitation of np Rydberg states of cesium atoms shows a dipole blockade at F\"{o}rster resonances corresponding to the resonant dipole-dipole energy transfer of the np + np → ns + (n + 1)s reaction. The dipole-dipole interaction can be tuned on and off by the Stark effect, and such a process observed for relatively low n (25 − 41) is promising for quantum gate devices. Both Penning ionization and saturation in the laser excitation can limit the range of observation of the dipole blockade