Measurement of magic-wavelength optical dipole trap by using the laser-induced fluorescence spectra of trapped single cesium atoms.

Based on the multi-level model, we have calculated light shifts for Zeeman states of hyperfine levels of cesium (Cs) 6S1/2 ground state and 6P3/2 excited state. The magic-wavelength linearly-polarized optical dipole trap (ODT) for Cs 6S1/2 |F = 4, mF = + 4ñ - 6P3/2 |F' = 5, mF = + 5ñ transition is experimentally constructed and characterized by using the laser-induced fluorescence spectra of trapped single Cs atoms. The magic wavelength is 937.7 nm which produces almost the same light shift for 6S1/2 |F = 4, mF = + 4ñ ground state and 6P3/2 |F' = 5, mF = + 5ñ excited state with linearly-polarized ODT laser beam. Compared to undisturbed Cs 6S1/2 |F = 4, mF = + 4ñ - 6P3/2 |F' = 5, mF = + 5ñ transition frequency in free space, the differential light shift is less than 0.7 MHz in a linearly-polarized 937.7 nm ODT, which is less than 1.2% of the trap depth. We also discussed influence of the trap depth and the bias magnetic field on the measurement results.