Ultracold-atom quantum tunneling through single and double optical barriers

We realize textbook experiments on Bose-Einstein condensate tunneling through thin repulsive potential barriers. In particular, we demonstrate atom tunneling though a single optical barrier in the quantum scattering regime where the de Broglie wavelength of the atoms is larger than the barrier width. Such a beam splitter can be used for atom interferometry and we study the case of two barriers creating an atomic Fabry-P\'erot cavity. Technically, the velocity spread of the atoms is reduced due to the use of a $^{39}\mathrm{K}$ Bose-Einstein condensate with no interactions. The potential barriers are created optically and their width is tunable due to the use of a digital micromirror device. In addition, our scattering experiments enable in situ characterization of the optical aberrations of the barrier optical system.