N−Qubit W State of Spatially Separated Atoms via Fractional Adiabatic Passage

An alternative scheme is presented to realize an N−qubit W state with distant atoms trapped in spatially separated optical cavities coupled by optical fibers via a fractional adiabatic passage. The present scheme is tolerant to device parameter nonuniformity and does not need to accurately control the experimental time by employing the fractional stimulated Raman adiabatic passage. In addition, the excited states of atoms are adiabatically eliminated and no additional qubit is required. Cavity decay, fiber losses and atomic spontaneous emission can all be greatly suppressed in the present scheme.