We calculate the quantum motion of ultracold atoms in an accelerating optical potential, and show how they may be used to observe Landau-Zener tunneling and Wannier-Stark ladders, two fundamental quantum effects in solid state physics. The optical potential is spatially periodic, yielding an energy spectrum of Bloch bands for the atoms. The acceleration provides an inertial force in the moving frame, emulating an electric force on Bloch electrons. [S0031-9007(96)00402-4]

In this paper we present a method to control the electronic position in a quantum dot array coherently with a two-electron model. In this novel phenomenon, we find that the external ac driving field has a good manipulative effect on the tunnelling, and therefore the penetrability of the barrier can be easily adjusted. Through studying the Floquet spectrum of the system, we find that it can be divided into two minibands. The upper miniband describes the physical process of states in which the two electrons stay in the same dot and the lower miniband describes the states in which the two electrons stay in different dots. The parameter regions in which the manipulation of tunnelling is investigated exactly correspond to the collapse zones of quasi-energy levels.

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