ONE-ATOM IN AN OPTICAL CAVITY - SPATIAL-RESOLUTION BEYOND THE STANDARD DIFFRACTION LIMIT

The position of a slow atom passing thro ugh a standing-wave light field in an ultrahigh-finesse optical resonator can be measured by observing either the intensity of the light transmitted through the cavity or its phase. Apart from the periodicity of the standing wave, both techniques allow to determine the position of the particle with a resolution much better than the standard classical diffraction limit Delta x greater than or equal to lambda/2. Position measurements with uncertainty < lambda/20 seem to be possible with all-optical techniques.