Sub-Half-Wavelength Atom Localization Based on Phase-Dependent Electromagnetically Induced Transparency

We present a realistic and efficient scheme for sub-half-wavelength atom localization. This scheme is based on the phase-dependent lectromagnetically induced transparency in a four-level system in the double-λ configuration. We use a strong bichromatic field (one component of which is standing-wave field) as the driving components, and a weak bichromatic field as the probe components. By choosing the collective phase of the four applied components, the atom is localized in either of the two half-wavelength regions with 50%
detecting probability when the absorption to the probe fields is detected.