State-insensitive trapping and guiding of cesium atoms using a two-color evanescent field around a subwavelength-diameter fiber

Abstract

We calculate the optical potentials, i.e. the light shifts, of the ground and excited states of atomic cesium in a two-color evanescent field around a subwavelength-diameter fiber. We show that the light shifts of the $6S_{1/2}\leftrightarrow 6P_{3/2}$ transitions can be minimized by tuning one trapping light to around 934.5 nm in wavelength (central red-detuned magic wavelength) and the other light to around 685.5 nm in wavelength (central blue-detuned magic wavelength). The simultaneous use of the red- and blue-detuned magic wavelengths allows state-insensitive two-color trapping and guiding of cesium atoms along the thin fiber. Our results can be used to efficiently load a two-color dipole trap by cesium atoms from a magneto-optical trap and to perform continuous observations.