Atom nanolithography with cold cesium atoms

The experimental set-up exploits a pyramidal funnel, made of two prisms and two mirrors arranged in the shape of an inverted pyramid with a small hole (1 mm × 2 mm) at its apex, mounted on a stainless-steel holder inside an ultra high vacuum system. The light for manipulating cesium atoms is produced by diode lasers operating around 850 nm, mounted in the external cavity configuration. The quadrupolar magnetic field for the pyramidal-MOT operation is produced by two coils in anti-Helmholtz configuration. The atomic beam leaving the funnel is characterized, i.e., its density, divergence, longitudinal velocity and temperature are measured. Induced fluorescence images, acquired using a CCD camera, and absorption measurements show a beam divergence of 25 mrad, a longitudinal velocity in the range 10-15 m/s (depending on the trapping parameters) and a flux up to 4 × 10⁹ atoms/s. The atomic beam diameter (FWHM) is 1 cm measured 30 cm downward the funnel apex. The deposition of cesium through a light mask on several kinds of substrates is then performed.