Sub-half-wavelength atom localization via phase control of a pair of bichromatic fields

Abstract

We propose a scheme of atom localization based on the interaction of the atom in the $\ensuremath{\Lambda}$ configuration with a strong bichromatic coupling field and a weak bichromatic probe field with equal frequency difference. One of the bichromatic coupling components is a standing-wave field, which imposes position information on the Rabi frequency. By varying the difference between the relative phases of the two bichromatic fields, the atom is localized in either of the two half-wavelength regions with 50% probability provided the population in the upper state is detected.