We report on the direct observation of an oscillating atomic current in a one-dimensional array of Josephson junctions realized with an atomic Bose-Einstein condensate. The array is created by a laser standing wave, with the condensates trapped in the valleys of the periodic potential and weakly coupled by the interwell barriers. The coherence of multiple tunneling between adjacent wells is continuously probed by atomic interference. The square of the small-amplitude oscillation frequency is proportional to the microscopic tunneling rate of each condensate through the barriers and provides a direct measurement of the Josephson critical current as a function of the intermediate barrier heights.

F. S. Cataliotti et al.
Josephson Junction Arrays with Bose-Einstein Condensates
Science 293, 843 (2001)

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Shining a blue detuned thin (2 μm) barrier we produce a double-well potential, which creates a Josephson-like junction for fermionic superfluids. By varying the interactions we investigate the population and phase dynamics between the two wells, observing the Josephson effect across the BEC-BCS crossover.

G. Valtolina et al.,
Josephson effect in fermionic superfluids across the BEC-BCS crossover
Science 350, 1505 (2015)

Light at 421nm will be employed for transverse cooling and for the Zeeman slower. Up to 1.2W of blue light is produced in a homemade frequency doubling cavity and is locked to the atomic line using saturated absorption spectroscopy in a hollow cathode lamp.

Light at 626nm will be employed for the magneto-optical trap (MOT). The red light is obtained from a commercial laser system and is locked to the atomic line using saturated absorption spectroscopy in a iodine cell.

Carlo Sias has been awarded with a SIR ("Scientific Independence of young Researchers") grant from MIUR ("Italian Ministry for Education and Research") for the development of the Ba⁺/Li experiment!